Once a year, in December, a meteor shower known as the Geminids appears in the sky. Peak activity occurs on December 13-14, making it one of the most active and consistent meteor showers of the year. The source that causes the Geminids is assumed to originate from the asteroid 3200 Phaethon. The Geminid meteors are often yellow or blue in color, and they are famous for their leisurely, beautiful motion across the sky.
Key facts about Geminid meteors
The Geminid meteor shower returns to the night sky from December 6–16, 2022.
The Geminid and Quadrantid meteor showers are significant because they are not generated by comets.
The night of December 13-14, 2022, is predicted to have the highest concentration of shooting stars.
Like the Perseids, Delta Aquariids, Arietids, and Eta Aquariids, the Geminids are a yearly meteor shower that disintegrates upon entering Earth’s atmosphere.
A meteor is the scientific name for any shooting stars. They are flammable space rocks that can be seen by the naked eye.
The Earth annually travels through the trail of dust left by the asteroid 3200 Phaethon, which is the origin of the Geminid meteor shower. Here we see Earth (a blue dot on a blue orbit) approaching this line. The 3200 Phaethon asteroid is currently located in the Pisces constellation.
The twin constellation, or “Gemini” in Latin, seems to be the source of the meteor shower. There, they were dubbed Geminids. However, the Geminid meteor shower does not actually originate from the constellation but from the 3200 Phaethon asteroid. Similarly, the Ursids take their name from a constellation: Ursa Minor, the Little Bear.
When is the ideal time to see the Geminid meteor shower?
The Geminid meteor shower lasts for 10 days, from December 6th to the 16th.
The International Meteor Organization predicts that the night of December 13–14 as the greatest night to see the Gemnids. From Tuesday night through Wednesday morning, that’s when the Geminids will be at their visible peak. And the real maximum will be at 1 pm UTC on December 14.
The sky is pierced by as many as 150 meteors each hour during the shower.
Bolides, or fireballs, are very bright objects that astronomers anticipate seeing.
The Geminid meteors reach their maximum height of about 60 miles (100 km) before they explode. This is the boundary between space and Earth’s atmosphere. In most cases, the meteors will not approach within 25 miles (40 km) of our planet.
Where and how can you get the finest view of the Geminids?
Beginning around sunset, this spectacular star shower can be seen. The origin of the meteor shower, the 3200 Phaethon, will still be quite high in the sky. And, because of Earth’s rotation, it won’t begin its ascent until much later. The greatest time to see the Geminid meteors is about 1 pm UTC in 2022, although you may see them all night long.
Away from the city’s bright lights! If you want to see more Geminid meteors, you need to leave the city and get to the countryside, or at least someplace with a black sky. Visibility is diminished by man-made lights like streetlamps and automobile headlights.
Clouds may prevent you from seeing the celestial show, but you can still watch it online in real time. Also, look up at the sky from a height of around 60 degrees.
The best time to begin your search is two hours after sunset. (Picture by Gregg Dindermann, courtesy of Sky & Telescope)
It’s odd that the Geminids are divided up by mass. This implies that the fainter and less brilliant Geminid meteors will be seen initially, with the brighter and heavier ones being seen at the peak.
The waning moon is a potential hazard to visibility. Because six days after the full moon, on December 13-14, the moon will greatly shine in the constellation Pisces, where 3200 Phaethon is currently located.
Put down your phone. Because for a few minutes at least, your night vision will be impaired by the glow of your screen. Allow your eyes twenty to thirty minutes to adjust to the low light levels.
Interesting aspects about the Geminids
In the Northern Hemisphere, the Geminids provide the most visible meteor shower of the year. In addition to being the brightest, the Geminid meteors may also be seen in a variety of colors.
Even though they are not coming from the constellation of Gemini, these meteors are still known as Geminids.
The widely accepted hypotheses place its genesis on the asteroid 3200 Phaethon. This celestial body, which is around 3.7 miles (6 km) in diameter, wasn’t discovered until 1983. It makes repeated passes around Earth’s orbit, leaving a trail of dust in its wake.
The radiant, or point of emission, for the Geminids is located very near the star Castor (the second-brightest object in the Gemini constellation), but of course, it is not the source of the Geminids.
The Geminid meteors travel at a speed of 22 miles (35 km) per second when they enter the atmosphere. To put it in perspective, it’s around one 100 times quicker than a bullet fired from a handgun. It’s interesting that this is merely a middling speed for meteors.
Name:
Geminids
Type:
Meteor Shower
Origin:
Asteroid 3200 Phaethon
Period:
04-20 December 2022
Maximum:
14 December 2022, approx. 2 pm CET, 1 pm UTC
Shooting stars per hour:
150 (in perfect conditions)
Radian:
Constellation Gemini
The FAQ about the Geminids
The Geminids—what are they?
Each year, the sky is lit up by a shower of meteors known as the Geminids.
When will you be able to view the Geminids?
Annually, between roughly December 6 and December 16, the skywatchers may get a glimpse of the Geminids.
When the Geminids will be at their maximum?
In 2022, on the 13th and 14th of December, you’ll see the most Geminids, but only at night and mostly on 1 pm UTC, December 14th.
Where is the best place to see the Geminids?
The ideal place to see the Geminids is away from any bright lights, however, they can be seen all across the planet.
When will Halley’s Comet next pass by? What was the spacecraft that arrived on comet 67P, and where is comet Leonard right now? How and where do comets get their distinctive shapes? What is the difference between a comet, an asteroid, or a meteor? Here, we’ll explain the distinctions between them.
They travel through our sky, leaving behind lengthy clouds of gas that provoke intrigue, curiosity, and even fear of a fall depending on the time, and they have humorous names like C/2021 A1, Halley, and 67P. Let’s explore the history of comets, from Halley’s to the more recent Neowise and Leonard, and even the renowned comet 67P, which was outfitted with the Philae spacecraft. These frozen things have captivated and terrified humans for millennia.
In 2023, what comet might we expect to see?
Predicting a comet’s visibility is difficult since it relies on so many variables, and their passage can only be computed a few months in advance. On May 13, 2023, comet 39P Oterma is expected to approach quite close to Earth, raising the possibility that it may be seen from Earth. Comet 103P Hartley may possibly make a close approach to Earth on October 13, 2023.
What is a comet?
The structure of a comet. (Image credit: Pearson Education)
A comet is a heavenly body formed long ago during the formation of the solar system from gases, rocks, and dust that have since frozen solid. These snowballs from space are the real deal. The Sun’s heat causes the comet’s material to melt as it approaches and passes close to the star. After that, the comet starts to eject a massive luminous shape, bigger than most planets, made of dust and gas.
When a comet is in a tight solar orbit, its size may range from a few miles to tens of miles. When its material begins to flow out, it creates a beautiful cloud of gas and dust that follows behind it for millions of miles, making it visible to us on Earth.
The comet develops two tails in its wake: the dust tail and the plasma tail. The first one is made of dust and is proportional to the speed with which the asteroid is moving. Being able to span millions of miles makes it the most impressive. The second is a gaseous structure known as an ionized tail or plasma tail.
These gas molecules are disassembled by the sun’s UV rays, making them emit light. A plasma tail may extend out into space for tens of millions of kilometers. They can reach 100 million miles in length (around 150 million km). Comet Hale-Bopp has been seen with a third sodium tail.
The composition of a comet
Comets emerge from debris left behind from when the Sun and planets were first created. As such, these objects serve as crucial eyewitnesses to the birth of our solar system. Comets are witnesses to those early moments. Because they did not undergo any changes since being frozen in the beginning.
Frozen gases, in the form of ice, boulders, and rock dust, make up a comet’s nucleus. Observations of comet 67P reveal that it is rich in carbon and that several chemical compounds previously unknown everywhere except on Earth have been detected on the comet. Therefore, it is possible that the components that made it possible for life to form on Earth came from space and were carried by heavy bombardment 4 billion years ago. In order to learn more, it would be necessary to analyze the makeup of several additional comets.
The biggest known comet
Comet Bernardinelli-Bernstein compared to other comets. Image credit: NASA / ESA / Zena Levy, STScI.
Currently, comet Bernardinelli-Bernstein or “C/2014 UN271” is the biggest comet in the sky. Observers didn’t directly see it until December 2021, and it wasn’t discovered until 2014. They measured its peculiar diameter and found it to be 85 miles, or 137 kilometers. Because of this, it is the biggest known comet, surpassing even comet C/2002 VQ94 (LINEAR). We now know this based on images collected by the Hubble Telescope in January 2022.
The difference between a meteorite and a comet
A comet is a celestial body that orbits the sun or another star. A core of ice and particles makes up its core. Some of its components transform into gas as it nears the Sun, leaving a bright trail behind the nucleus stretching for millions of miles. Meteorites, on the other hand, are pieces of rock and metal that fall to Earth after entering the atmosphere and burning up. Comets and meteorites are not similar in composition or origin.
The difference between a comet and an asteroid
Asteroid belt
Asteroids, which circle the Sun and may be either rocky or metallic, are one such kind of object. There are two asteroid-rich regions in our solar system, the main asteroid belt, and the Kuiper belt. Both of these regions are now thought to have existed because a planet never formed there. The rocky debris that may have coalesced into a planet during the formation of the other planets is still present in this region. Asteroids are the undeveloped embryos of planets that failed to complete their accretion process.
In contrast, comets are icy entities made of gas trapped in ice and dust from the early solar system’s creation. These objects have been collected from all around the solar system and are now being held in the Oort cloud, a large collection of comets near the solar system’s outskirts. When a comet approaches the Sun, the ice at its core melts and converts to gas, leaving behind a lengthy, distinctive path that can be seen from Earth.
Where do comets come from?
The Oort cloud is where most scientists believe comets originate from. This cloud is a spherical structure that fills the whole solar system with countless frozen particles. As a result, it serves as a genuine comet reservoir. Once in a while, a neighboring planet’s gravitational pull will lead one of these objects to detour from its original path.
The comet’s orbit might shift, bringing it closer to the Sun, where it could be thrown off course. Some comets make a single close approach to the Sun and then continue on their orbits far from the star. While others may be seen from Earth because their orbits are so elliptical that they often pass at a relatively close distance to the Sun.
Were dinosaurs wiped off by a comet?
The Yucatán Peninsula in Mexico was hit by an asteroid 66 million years ago, when Earth was teeming with dinosaurs. The extinction of the dinosaurs and 75% of all other life on Earth can be directly attributed to the collision of this object.
However, in February 2021, two academics released a paper in the journal Scientific Report that offered a new idea to explain the phenomenon. They hypothesized that the object that struck Earth was a piece of a comet that had gotten too close to the Sun and been torn apart by the Sun’s gravity. This impact would have resulted in the formation of the well-known Chicxulub crater and a tsunami, both of which proved to be disastrous for a wide variety of living forms.
When did Halley’s Comet last appear?
Halley’s Comet is without a doubt the most well-known comet in history. Even before it was formally discovered in 1758, this comet had been seen multiple times. The watchers had thought they were seeing a new comet each time.
Many years after this date, in 1835, 1910, and 1986, this comet made fresh crossings that were more or less impressive. Every 76 years, to be precise, and the next one won’t happen until 2061.
Where is Comet Leonard?
Greg J. Leonard, an astronomer, and geologist who discovered comet Leonard in January 2021 and gave it its name, predicted that on January 3, 2022, the comet will come very near to Earth, resulting in a sequence of extraordinary photographs. After that, the comet started to leave our planet and go back to the solar system’s outskirts. It began to dissolve in February 2022, when its nucleus and hair began to fall out.
When did comet Neowise last pass earth
In July 2020, astronomy fans everywhere were giddy about Comet Neowise, also known as C/2020 F3. Many pictures, like the one NASA released, have been inspired by its arrival. The Parker Solar Probe captured the image of the comet, which shows off its distinctive “hair” and “double tail.”
The comet, which had been photographed from every conceivable direction by astronomers all around the globe, has now returned to the Oort cloud. There is a true reservoir of comets in this enormous cloud of tiny ice particles located after Neptune. If Neowise has piqued your interest, you won’t be able to get a glimpse of it for another 6,800 years.
How large is comet 67P?
The weird shaped comet 67P captured by Rosetta. Credit: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0
Comet 67P/Churyumov-Gerasimenko was discovered near Kiev, Ukraine in 1969. This interestingly shaped comet is around 2.5 miles (four kilometers) in length. However, despite its massive size, it is capable of floating. Its density is comparable to that of cork. The comet’s overall form is remodeled when the ice that makes up its surface is sublimated during its many close approaches to the Sun. According to scientists, there are cliffs, plains, and faults to be discovered.
Comet 67P has been explored in great detail by scientists because of the Rosetta probe and its robotic Philae. Following a trip lasting more than a decade aboard the Rosetta probe, the latter finally touched down on the comet’s surface in November of 2014 after traveling 4 billion miles (6.4 billion kilometers) through the Solar System.
The Philae robot, which was equipped with a soil drilling instrument and many pieces of equipment to study the samples it obtained, communicated with Rosetta and relayed crucial data on the comet’s composition until the end of contact in July 2015. In November of 2021, 67P came back to see us again before relocating “permanently”. Since it is unlikely to travel this way again until 2214, it will have a very long voyage ahead of it.
The best way to see a comet in the night sky
The comet’s brightness will determine whether or not it can be seen with the naked eye. This happened in July of 2020 with the very brilliant comet Neowise. To fully appreciate the event, though, astronomical binoculars or a telescope are a must.
When a comet is visible to the human eye, it can be captured on film using just a basic camera and some manual controls. Exposures of 20 seconds or longer at ISO 1600 (minimum 800) need to be used, along with a wide-angle lens. It’s best to reduce the ISO if light pollution is significant.
You may play with the composition by putting the comet in a unique place, such as high in the sky, over a tree, or in a valley between two mountains. To avoid fuzzy photos while taking them without a tripod, try setting the timer on your camera instead.
Asteroids are potentially catastrophic objects of various sizes in our solar system. In spite of how remote the possibility of an asteroid crashing into Earth is, it is still a very real threat. In the neighborhood of 180,000 tons of dust and meteorites fall to Earth each year. These objects tend to be quite diminutive. On the other hand, a massive asteroid may pose a danger to Earth. NASA and other space organizations keep an eye on the paths of some huge objects in case they collide with Earth. Both Apophis and Bennu, asteroids that will pass close to Earth in 2029, fit this description. Even though their paths don’t seem dangerous right now, the planets’ gravitational pull might alter their paths and lead to a collision in the future.
What is an asteroid?
An impression of the asteroid belt. Image credit: NASA/JPL-Caltech
An asteroid is a celestial object with an orbit around a star. Made of metals and rocks, they testify to the birth of our solar system. Asteroids, it is widely believed, are stony debris that failed to coalesce into planets.
These came from the main asteroid belt, which is the region of the solar system between Mars and Jupiter and includes hundreds of thousands of asteroids. Scientists believe that Jupiter’s gravity has stopped a planet from forming in this region. It follows that the asteroids represent the unborn planet’s embryos.
These chunks of rock are now circling the Sun in an area known as the asteroid belt. However, sometimes the gravity of a planet like Mars or Jupiter may cause them to detour from their original path. Once they break off from their original orbit, they are classified as NEOs because they have the potential to enter Earth’s orbit.
The most well-known asteroids
Ceres, the first asteroid ever discovered, was found by Italian astronomer Giuseppe Piazzi in 1801. Since this discovery, astronomers’ attention has shifted away from monitoring asteroids and toward the study of planets and stars. However, asteroids provide insight into the early history of Earth and the Solar System. However, although the vast majority of these aliens maintain their anonymity and quietly develop in their orbit, others are well-recognized and have names. Sometimes scientists would follow them around and watch them from every possible vantage point.
Asteroid Apophis
The asteroid Apophis was first seen in 2004, and its journey has been meticulously tracked ever since. The closer it gets to Earth in its orbit, the more likely it will crash into our planet. Fear and debate are fueled by this possibility, despite NASA’s comforting findings that nixed it years ago.
It’s not a slutty stone, and with good reason. At 1,150 feet (350 meters) in diameter and 27 million tons in mass (30 million US ton), the asteroid is a formidable presence in the solar system. In 2021, it came within 10.5 million mi (17 million km) of Earth (44 times the distance between the Earth and the Moon). Nothing about it posed any kind of danger from this far out. Its future passing has long caused concern among experts. In fact, in 2029, Apophis will be significantly closer to Earth thanks to its orbit, passing within 20,000 mi (32,000 km or one-tenth of the distance between Earth and the Moon) of our planet. To rephrase, it will make a close pass between the Earth and a few geostationary satellites.
However, NASA has told us that a collision is not possible, contrary to the dire predictions of certain periodicals. An American government organization has concluded that this asteroid poses no threat to Earth during the next 100 years.
Asteroid 2001 FO32
Asteroid 2001 FO32
Astronomers were able to get a good look at the strange asteroid 2001 FO32 on March 22, 2021, when it passed within 1.25 million mi (2 million km) of Earth. This asteroid’s unusual quality is its velocity.
The asteroid 2001 FO32 was reportedly the race leader because it was “faster than most asteroids,” as stated by NASA, as reported by the publication Sciences et Avenir. At 79,500 mi/h (128,000 km/h), it was adding about 0.6 miles every second to its total distance traveled. Having a diameter of 0.35 mi (550 m), it was too small to be seen from Earth without a telescope.
Comet 2020 VT4
It is not always possible to predict which asteroids will be seen before they approach the Earth. Some of these asteroids are too near to the Sun for scientists to spot in advance of their arrival. In 2020, asteroid 2020 VT4 made a surprise flyby approximately 235 mi (380 km) over the Pacific Ocean, causing widespread damage. This indicates that it made its way between Earth and a group of geostationary satellites. The distance of VT4 from Earth’s surface is the closest of any passing asteroid.
If this object had impacted Earth, it would not have posed any threat to mankind due to its modest size.
The Little Prince, or Asteroid B612
It’s likely that one of the most well-known asteroids is B612 from Antoine de Saint-Exupéry’s Little Prince. Some readers could suspect that the author has just made up this heavenly body. Still, it does exist, or at least nearly does. The German astronomer who discovered the asteroid in 1906 gave it the designation 612 (without the B). A second asteroid, 46610 Besixdouze, was found on October 15, 1993, and was named after the Little Prince.
Asteroid Bennu
Bennu, found in 1999, is one of the asteroids considered a “danger” to Earth, despite the fact that the probability of a collision remaining at its current level is very low.
After dancing around the asteroid for two years, the Osiris-Rex mission was able to gather surface samples for a NASA investigation. The asteroid measures 1650 ft (500 m) in diameter. In 2023, we’ll bring those samples back to Earth for analysis.
After analyzing its predicted path, NASA determined that the probability of this asteroid colliding with Earth was less than 0.057%. Scientists from NASA have concluded that there is a 99.94% likelihood that Bennu is NOT on an impact trajectory.
NASA warns that if the asteroid’s track changes and it comes closer to Earth, the threat will increase. This is possible if the object enters a region where the Earth’s gravity alters its path. Scientists have estimated that this may happen in 2135. That would put the crash in the year 2182. It is predicted that the crater will be between 3 and 6 mi (5 and 10 km) in diameter.
Which asteroid threatens Earth?
When the Apophis asteroid was discovered in 2004, scientists were alarmed by predictions that it would collide with Earth in 2029. The asteroid is around 1,150 ft (350 m) in length. Despite the many alarmist headlines released in different media, it turns out that these worries are unjustified, since the asteroid’s course rules out any collision with Earth over the next 100 years.
NASA has been keeping a tight check on this asteroid ever since the scare, and it seems like it will come within touching distance of Earth, making it visible to the naked eye. We have a spectacular show in store for us, but there is no end of the world in sight.
What are dangerous asteroids?
Objects that pass through Earth’s orbit, known as near-Earth objects (NEOs), are often mentioned while discussing the dangers posed by falling asteroids. Based on their size and orbital distance from Earth, several of these asteroids pose a threat to our home planet. If an asteroid with an absolute magnitude, or brightness, of less than 22 passes within 0.05 au (4.64 million mi or 7.48 million km) of Earth, it is classified as potentially hazardous. The brighter an object is, the smaller its absolute magnitude value. The bigger the asteroid, the lighter it reflects, hence the brighter it seems.
The likelihood of encountering an object big enough to pose a threat to humanity is low but not zero. The extinction of the dinosaurs occurred 66 million years ago as a result of a catastrophe of this sort.
Since we now have means of avoiding collisions, this danger may be mitigated to some extent. But what would we do if it turned out that a massive asteroid was about to smash into Earth sometime in the next decade? So, what do we have at our disposal?
Evacuating the affected region is now regarded as the only viable option. But what if the danger is much more than that? Planetary defense initiatives are currently researching and developing methods to properly detect potentially hazardous asteroids and deflect them.
The asteroid that wiped off the dinosaurs
Many ideas have been proposed to explain the rapid extinction of the dinosaurs 66 million years ago, with new versions being introduced on a regular basis to account for new findings. One popular theory is that the stunning crater of Chicxulub in the Mexican state of Yucatán was produced by the impact of an asteroid or an asteroid fragment. It would have set off a chain reaction leading to a severe disaster, wiping out numerous animal and plant species, maybe even the non-avian dinosaurs.
The 112 mi (180 km) wide Chicxulub crater was created by an asteroid, but no one knows for sure which one. A report from 2007 in Nature implicates an asteroid with the designation 298 Baptistina. However, this finding has not been accepted universally by the scientific community.
The Deccan Traps, which are volcanic landforms in India, are the focus of the second leading hypothesis that attempts to account for this extinction event by releasing massive amounts of gas into the atmosphere. This time it wasn’t triggered by meteorites; instead, the extinction of the dinosaurs was likely precipitated by a period of massive volcanic eruptions that disrupted the global climate.
How to observe an asteroid?
A number of factors, including the asteroid’s size and distance from the Sun, determine whether or not we can see it. When certain asteroids approach so close to Earth, we may see them with the naked eye.
In other cases, you’ll need binoculars or a telescope to see the spectacle.
The inquisitive may now use a NASA-created online tool to track the motions of several asteroids and comets. You’ll be able to watch for aliens if they ever arrive.
The biggest asteroid in the universe
With a diameter of 587 mi (946 km), Ceres is the biggest main-belt asteroid. In addition, it is the tiniest of the dwarf planets in our solar system. The size of the asteroid that generated the massive Chicxulub crater is believed to be about 7.
This Kuiper belt object is the next one in line after Neptune. A diameter of 775 mi (1,250 km) has been calculated. Larger objects, like Eris, have since been discovered in the Kuiper belt, and these objects are now considered to be dwarf planets. There are a lot of big objects in this faraway region, and studying them is challenging for a number of reasons, not the least of which is their great distance.
The distinction between asteroids and meteorites
The term “asteroid” refers to any astronomical body circling a star that is composed mostly of rock and metal. As a result of course corrections, these objects sometimes approach Earth. A meteorite is an asteroid rock that has survived its fall into Earth’s atmosphere. As a result of the data they provide on the asteroids they came from, these meteorites are of great scientific significance.
What is the DART mission? Here is everything there is to know about it. Thousands upon thousands of asteroids speed through space with many of them routinely passing within Earth’s orbit. A regional or perhaps worldwide disaster could be triggered if one of them were to arrive on a collision track with Earth. With its DART mission, NASA is exploring whether or not this may be avoided; for the first time, humankind will seek to alter an asteroid’s course by use of a ram probe.
What could be done if an asteroid is headed in the direction of Earth? According to NASA, a more effective defense would be to use an unmanned spacecraft to deflect the asteroid. On September 26, 2022, NASA’s DART mission will put this kinetic deflector approach to the test.
How do you avoid an asteroid collision?
The risk is real: Earth has been bombarded by space debris several times during its existence. The impact of the 6.2-mile (10-kilometer) wide Chicxulub asteroid 66 million years ago terminated the Cretaceous epoch and wiped out the dinosaurs, while other impacts have created worldwide disasters and monumental mass extinctions. The Tunguska event of 1908 and the Chelyabinsk meteor explosion in February 2013 proved, however, that even tiny fragments may wreak devastating harm.
About 25,000 asteroids, each about 500 feet (150 meters) in size, orbit in the neighborhood of the Earth and often pass through the Earth’s orbit. Although many incidents still go unreported.
It’s just a matter of time
Small chunks up to 3.3 feet (1 meter) in size continue to impact Earth practically daily but are burned up in the atmosphere before reaching the surface. Asteroids up to 1,000 feet (300 meters) in size are expected to strike every few thousand years, and asteroids the size of the Chelyabinsk meteor are seen on average once every 50 years. They are big enough to obliterate a whole city of millions. It’s not a matter of if, but rather when, the next major impact on Earth will occur.
What could be done if an oncoming asteroid is noticed in time? Whether humanity still has time to adopt countermeasures for an approaching asteroid depends on the size of the asteroid and the time left before the impact. When the threat is known decades in advance, the “gentle” “Gravity Tractor” defense could be all that’s needed: Using the gravitational pull of a large probe brought in close proximity to the asteroid, you can divert the asteroid off an Earth collision trajectory.
The kinetic deflector
A spacecraft smashes the asteroid and attempts to divert it off its crash route in an asteroid defense via a kinetic deflector. (Image: INASA/Johns Hopkins University APL)
But in reality, it is more probable that the asteroid will go undetected until it is too late. Because many possible Earth-orbiting asteroids are hard to spot in advance due to their dimness and their orbital distance to the Sun. The 330-foot (100-meter) asteroid called “2019 OK,” for example, was only discovered 12 hours before its closest approach in 2019. Thankfully, it was passing Earth at a distance of barely one-fifth that of the moon. After that point, no amount of protective measures will be able to prevent an impact.
However, there is still hope for an asteroid deflection if an asteroid on a crash track is discovered months or perhaps years in advance. The kinetic deflector approach is generally thought to be the best in such a scenario. As part of the strategy, the heaviest feasible spacecraft is sent in the direction of the asteroid to smash it at a specific angle. If the collision happens early enough, the force of the impact can deviate the fragment off its trajectory, and a deviation of only a few millimeters or a modest slowing is enough to prevent a collision with Earth.
But there is more to it
However, such a deflection is notoriously difficult in reality. The asteroid probe has to make a perfectly timed and hard collision with the asteroid. Too much of an off-angle impact will just alter the asteroid’s spin and not its course. The deflecting impact will be insufficient if the momentum is too low. This method requires the most precise data available regarding the asteroid’s course, spin, and size in order to precisely plan the collision.
If the asteroid is porous, most of the impactor’s energy might be absorbed instead of dissipated. The spacecraft’s collision might cause the asteroid to fracture if it is fragile or made of debris that is only weakly held together. Multiple, potentially catastrophic chunks can still head toward Earth in this case.
Given these challenges, NASA is conducting its first practical tests of kinetic deflection, called the DART Project, as a means of asteroid deflection, serving as a kind of “dress rehearsal” for the real deal.
Target object of the DART
A double asteroid as the impactor
Dimorphos’ new orbit after the collision of the DART satellite. The LICIACube will track the collision and broadcast pictures of the impact back to Earth. (Image: NASA/DART)
This is no easy feat since the whole collision must take place millions of miles from Earth to redirect an asteroid off its crash course with Earth. However, if the asteroid is so far away, the scientists may not be able to determine its exact nature, rotation, or mass before sending out the defensive probe since it will be beyond the precision of current Earth-based telescopes.
The selection of the test asteroid for DART
With the “Double Asteroid Redirection Test,” or DART, NASA is exploring the limits of an asteroid defense mission’s success and the hazards it faces. If an asteroid were to be headed toward Earth, a kinetic deflector, like the one shown by DART, would be the only way to stop it. DART’s mission is to change an asteroid’s orbit, so it can not collide with Earth.
The primary stipulation for the DART is that the experiment must not endanger Earth in any way. Even after an unsuccessful deflection, the target asteroid must follow a course that moves it as far away from Earth as feasible. However, in order to accurately assess the ramming’s effects, the candidate asteroid must be rather near. Thus, it has to be visible with large telescopes.
Didymos and its moon Dimorphos
Size comparisons of DART, Dimorphos, and Didymos. (Image: NASA/Johns Hopkins University APL)
The 1996-discovered twin asteroid Didymos satisfies these requirements for the DART mission. Didymos, the 2560-foot (780-meter) asteroid, and Dimorphos, its moon, measure around 525 feet (160 meters) in diameter. Because of their eccentric orbits, they both swing from the furthest distance from the Sun outside of Mars’ orbit to the closest distance to the Sun within Earth’s orbit. Accordingly, both are circling the Earth and are part of the class of asteroids that, although not immediately dangerous, may one day approach Earth.
This is also why the DART mission isn’t actually aimed at the asteroid Didymos itself. Because there’s too much of a chance that the asteroid may be redirected in such a manner that it would eventually crash on Earth. The moon of the asteroid Dimorphos (Greek for “two forms”) is the actual target of the DART. Due to the stability of its orbit around Didymos, any deviation will only alter the minor-planet moon’s path relative to Didymos.
Observing Dimorphos with transits
When Dimorphos passes in front of his parent asteroid Didymos, the change in brightness allows scientists to calculate its orbital period. (Image: NASA/Johns Hopkins University APL)
While in orbit around Didymos, the asteroid moon also travels directly in front of it. Due to this predictable transit, astronomers have been able to estimate Dimorphos’ orbit and size using just Earth-based telescopes. This tiny moon takes 11 hours and 55 minutes to complete one orbit around its parent asteroid. During this time, the distance between them stays at just approximately 0.73 miles (1.18 kilometers).
The DART mission’s before-and-after planning requires a high level of foreknowledge about the asteroid system. Dimorphos’ orbit around its parent asteroid may be significantly altered if the DART probe collides with the moon at just the proper location and velocity. This deflection, at least in the model predictions, is expected to become apparent during the transit phase. As a result of the impact made by DART on the smaller asteroid in the Didymos system, its orbital period will be altered by at least 73 seconds.
The Didymos-Dimorphos binary asteroids will be within observing distance of Earth at the time of the DART’s collision on September 26, 2022, at a distance of just around 6.85 million miles (11 million kilometers).
Almost indistinguishable from the actual threat
However, there is a second reason why the Didymos system is well suited as a test case for the DART: its two components are illustrative of prospective asteroid impactors on Earth’s course. Dimorphos, with a diameter of around 540 feet (165 meters), is huge enough to cause widespread destruction in the case of an impact on Earth. While its size is comparable to that of probable next-catastrophic-impact asteroids, it is not one of them.
The composition of the target asteroid of the DART mission is also quite similar to that of the asteroids that are flying close to Earth. Didymos’s composition matches that of an “L/LL chondrite” meteorite class according to the analysis of its visible and near-infrared spectra. And this is the composition of most meteorites that strike Earth. The experimental findings of the DART collision will be used for a wide variety of planetary defense research.
Order of events of the DART mission
Specifications of the DART spacecraft
The DART probe places itself at the ideal impact point by autonomously navigating its course. (Image: NASA/Johns Hopkins University APL)
The DART spacecraft has been traveling toward the asteroid Dimorphos since it was launched on November 24, 2021. The asteroid moon Dimorphos will be rammed by the spacecraft on September 26, 2022, at 23:14 UTC, in an attempt to knock it out of orbit. This will be the first-ever test of a technology designed to protect Earth from asteroids. The DART mission is outfitted with various high-tech enhancements that allow this to happen.
The impactor probe used in the DART mission seems plain at first glance: The dimensions of its hull are 3.9 by 4.3 feet (1.2 by 1.3 meters), making it about the size of a soda machine. During the roughly 10-month approach, the DART probe has been powered by two solar panels, each of which is a good 26 feet (8 meters) in length. An experimental ion drive generates thrust by electrostatically accelerating and ejecting xenon ions in a magnetic field. DART has 12 hydrazine-fueled classical maneuvering thrusters for course corrections and fine-tuning of the final approach to Dimorphos.
DART’s autonomous target acquisition and approach
The DART spacecraft from two perspectives. (NASA)
The DART probe has a navigation system that is considerably sophisticated. This is due to DART’s ability to fine-tune its trajectory on its own. The data from the DRACO camera, a tiny telescope with a focal length of around 8.3 inches (21 cm), and a high-resolution digital image sensor are placed on DART for this purpose. High-resolution photos captured by the camera will reveal the precise location and shape of Didymos and Dimorphos.
The spacecraft’s autonomous navigation system records these photos with location and attitude data. About 4 hours before the crash with Dimorphos, at a distance of 56,000 miles (90,000 kilometers) from the target, this SMART Nav system will assume complete control of the DART probe. The navigation system will initially perform an evaluation of the data in order to pinpoint the precise locations of Didymos and its moon Dimorphos using custom algorithms. An hour before impact, Dimorphos will appear as a small 1.5-pixel light point.
The navigation system will then be able to make autonomous decisions about whether or not trajectory modifications are required, and the DART probe’s correction jets will receive new commands. When there are only 930 miles (1,500 kilometers) left between Dimorphos and DART, the asteroid in DRACO images will be around 22 pixels in size and it will be too late for DART to make any changes at this point. When DART is around 460 miles (740 kilometers) away from the target, it will be on a collision track with Dimorphos in two minutes. The probe will now just cover the rest of the distance.
The impact
The DART probe will crash on the surface of Dimorphos at a speed of around 14,000 miles (22,000 kilometers) per hour. DART weighs only 1,260 pounds (570 kilos), whereas the asteroid moon Dimorphos is predicted to weigh over 11 billion pounds (5 billion kilograms). Therefore their collision is more like a bug landing on an elephant. The impact’s relatively small impulse might not seem like it would accomplish anything.
This, however, is not true. The 540 feet (165-meter) rock will receive a little push from the high velocity of the DART collision. In addition to blasting between ten thousand and a hundred thousand pounds of debris into space, the impact will also create a hole in the asteroid’s surface. The force exerted on Dimorphos will be greater than that of the hit alone because of the rebound of this ejection. The combination of this amplified ramming action and the collision is enough to cause a little shift in the asteroid moon’s kinetic energy and knock it off of its orbit.
After DART crashed onto Dimorphos, the spacecraft will be destroyed but the scientific investigation will only be getting started.
Consequences of the DART Impact Event
What will happen to the massive Dimorphos-moon once the tiny DART spacecraft crashes into it? Will the massive asteroid be able to be steered out of orbit by kinetic deflection? How did scientists successfully predict the collision characteristics of the DART-Dimorphos event essential for a deflection?
LICIACube as the direct observer
The Italian Space Agency constructed LICIACube for the impact between DART and Dimorphos to send the collision images to Earth. (Image: (NASA/Johns Hopkins APL/Ed Whitman)
The LICIACube mini-satellite will report back the first data on the DART’s impact results and its effects on Dimorphos’s surface. This mini-satellite will ride behind the DART probe before it collides with the Didymos double asteroid, and its mission is to check out the impact area. Self-propelled with its maneuvering thrusters, it’s programmed to move into an observation point 15 days before the collision, which has already been initiated on September 11th.
LICIACube stands for Light Italian CubeSat for Imaging Asteroids. And the observations and documentation from this courageous little reporter will provide insights scientists couldn’t gain any other way. Using two optical cameras, LICIACube will capture the moment the DART spacecraft crashes on the surface of Dimorphos. Three minutes after the impact, LICIACube will adjust its course to fly near the DART’s crash location.
Images of the crater, the ejected material, and the type of debris of the DART impact are to be provided by this mini-probe. These photographs, together with the last close-ups captured by DART’s DRACO camera before the collision, will provide crucial details regarding the Dimorphos’ make-up, nature, and reaction.
A view of the Dimorphos orbit
Around the same time of the collision, a dozen or more very powerful telescopes on Earth will be aiming toward the Didymos system. The pair of asteroids are 6.85 million miles (11 million kilometers) away from Earth and are only a tiny speck of light even with the best telescopes. But we will be able to see from Earth the periodic variations in brightness of this light, which are set off by the transit of the moon Dimorphos in front of its parent asteroid.
A little shift in transit timing would indicate that the DART probe’s collision deflected the asteroid moon. Astronomers may roughly infer the strength of Dimorphos’ kinetic momentum and the extent to which its trajectory shifted in magnitude to find out whether the asteroid was successfully deflected and the DART mission was a success.
The essentials for the “genuine deal”
The events of DART’s mission definitely won’t be the basis for a Hollywood blockbuster, but the future of Earth’s safety is equally at stake. The ultimate goal of the DART mission is to demonstrate that human beings can deflect an approaching asteroid. If a similar-sized rock is ever found on a collision path with Earth, the knowledge and expertise gained from the DART test in the Didymos system will be invaluable.
Where to watch DART’s collision live
On Monday, September 26, at 4:14 p.m. PT / 7:14 p.m. ET, the spacecraft DART will crash with Dimorphos. Live coverage will start on NASA’s YouTube channel, and the NASA TV at 3 p.m. PT / 6 p.m. ET.
You can also see DART’s position live in the official NASA webpage.
Aftermath of DART
HERA, a spacecraft bound towards the Didymos system
This deflection mission won’t be completed right away despite the DART spacecraft’s collision with the asteroid moon Dimorphos and subsequent studies of the immediate repercussions.
HERA, a European spacecraft, will be launched in 2024 toward the Didymos system and arrive in 2026. For the first time, it will use on-site scientific instrumentation to explore the effects of this kinetic deflection. The HERA spacecraft will scan Dimorphos’s surface topography to an accuracy of within 33 feet (10 meters) using its LIDAR measuring system, camera, and mid-infrared scanner in order to examine the impact crater and any other changes to the surface that may have resulted from the collision.
More crucially, HERA will finally provide us with more accurate information on how far the DART probe steered away from its intended target. The rotation, mass, and orbit of Dimorphos and Didymos will be directly measured, unlike with terrestrial observatories. One way HERA will achieve this is by pointing its laser towards the parent asteroid and picking up the minute wobble caused by the small moon’s gravity. Additionally, HERA will do many near flybys of Dimorphos, transmitting data back to Earth each time. Scientists on the ground will be able to determine whether the asteroid moon’s gravity has altered the signals and, if so, by how much.
Milani: What are Didymos and Dimorphos made of?
The asteroids’ surface will be mapped by the CubeSat Milani, which will also examine the expelled dust. (Image: ESA/Science Office)
However, HERA isn’t traveling alone; it’s accompanied by two smaller satellites (CubeSats) that carry their own sets of equipment and will take readings that supplement those taken by HERA. The Milani minisatellite will use a hyperspectral camera and spectrometer to determine the elemental make-up of Dimorphos and Didymos.
This will also enable scientists to compare the composition of its surface to that of known meteorites and minerals, such as that of the DART crater and its ejecta. Milani also has an onboard analyzer calibrated to detect dust particles between 200 and 400 microinches (5 to 10 micrometers) in diameter. Scientists can use it to learn more about Dimorphos’ composition by studying the dust thrown up by the collision.
Juventas: First radar view into the interior of an asteroid
For the first time, radar will be used by the CubeSat Juventas to illuminate an asteroid’s interior. (Image: ESA/Science Office)
HERA’s companion CubeSat, Juventas, will be investigating the asteroids’ composition and dynamics up close. It is equipped with a miniature replica of the radar sensor used by ESA’s Rosetta comet mission to survey 67P/Churyumov–Gerasimenko, making it the smallest radar system ever sent into orbit. The Juventas radar system will carry out the same task at Didymos and Dimorphos. To do this, it will set up 4 radar antennas, each measuring 5 feet (1.5 meters) in length, and radiating radar waves with circular polarization. The incoming and outgoing signals from Dimorphos’ interior will be recorded and decoded simultaneously.
In order to get accurate readings, the tiny radar satellite Juventas will fly within 1.85 miles (3 kilometers) of Dimorphos at a slow enough speed to get high-resolution data despite the radar’s low power. The radar scan of an asteroid by Juventas will be the first of its kind which will greatly expand the understanding of asteroids. The reason for this mission is that the outside of an asteroid does not actually portray its interior accurately.
Determining whether Dimorphos is made of solid, compact rock or a loosely formed “pile of debris” will be crucial for future asteroid defense. This data, together with measurements of the DART deflection experiment will aid scientists in improving and adjusting the models and calculations used to plan such defensive operations to protect Earth from asteroids in the future.
As every year, the mild summer evenings are favorable for prolonged observation of the sky, especially during the Perseids. It is certainly the most popular meteor shower visible from the northern hemisphere of the year. But what are perseids, what causes them and where are they coming from?
The Perseids are active from July to September each year and usually peak in mid-August. They are considered to be the “best” meteor shower of the year, as they are one of the most abundant – 50 to 100 meteors observed per hour on average in the sky. With very fast and bright meteors, Perseid meteors frequently leave long “trails” of light and color behind them as they pass through Earth’s atmosphere, allowing skywatchers to easily notice them.
Key Takeaways: Perseids
The Perseid meteor shower is an annual celestial event that takes place from late July to mid-August. It stands out as one of the most renowned and reliably occurring meteor showers.
These meteor showers stem from the remnants left behind by the Swift-Tuttle comet. As our planet traverses through this residue, the particles incinerate upon entry into our atmosphere, resulting in luminous streaks of light famously referred to as meteors or, colloquially, “shooting stars.”
Typically, the Perseid meteor shower culminates in intensity around the period of August 11–13 each calendar year. During this span, onlookers can anticipate an augmented count of meteors adorning the heavens.
Perseid meteors frequently exhibit brilliance and rapid motion, leaving evanescent trails of light in their wake as they disintegrate. Certain meteors might even leave behind enduringly glowing trails, often termed “persistent trains.”
For optimal Perseid meteor gazing, seek out a location distant from urban luminosity, providing an unobstructed and clear panorama of the firmament. The prime times for observation fall within the pre-dawn hours when the radiant point, the apparent source of the meteors, ascends higher in the sky.
Emanating from a point in the constellation Perseus, these meteors are dubbed Perseids, signifying their celestial origin.
This composite mostly contains Perseid meteors. They all seem to be streaking in the same direction. Image Credit: NASA/MEO.
A meteor is a space rock, or meteoroid, that enters the Earth’s atmosphere. As it falls toward Earth, the resistance – or drag – of the air on the rock makes it extremely hot. This bright trail is not actually the rock, but rather the hot air and glowing dust as the hot rock passes through the atmosphere and disintegrates.
Where Do Perseid Meteors Come From?
Meteors come from the remnants of comet particles and broken pieces of asteroids. As comets approach the sun, they see their ice evaporate and pulverize tiny pieces of rock, forming a cloud of small rocky particles. Each year, the Earth passes through these trails of debris, which collide with our atmosphere and disintegrate to create these fiery and colorful trails in the sky. The peak of a shooting star shower corresponds to the peak of meteor activity when the Earth passes through the densest part of the debris shower.
109P/Swift-Tuttle.
The space debris that interacts with our atmosphere to create the Perseids comes from comet 109P/Swift-Tuttle. It was discovered in 1862 by Lewis Swift and Horace Tuttle. Its nucleus measures 16 miles (26 kilometers) in diameter, nearly twice the size of the meteor that is supposed to have led to the disappearance of the dinosaurs, and four times faster: it goes around the Sun in 133 years. It was Giovanni Schiaparelli who realized, in 1865, that this comet was at the origin of the Perseids.
As the largest object in the solar system (except for the Moon) to pass repeatedly close to Earth, the movements of Comet Swift-Tuttle have been meticulously studied by scientists and have been predicted for many years. Its most recent “perihelion”—the point in its orbit where it comes closest to the Sun—was in 1992, and the next one will not occur until July 12, 2126.
The point in the sky from which the Perseids seem to originate—their radiant—is the constellation of Perseus, which gave the Perseids their name. Although the constellation the meteor shower is named after helps the observers determine which shower they are looking at on a given night, the Perseus constellation is not the source of the Perseid meteors.
While a shooting star often lasts only a fraction of a second in the sky (with an average speed of 30 mi/s or 50 km/s), it is best to watch a large portion of the sky for at least 30 minutes beforehand for the eye to get used to the darkness. This should be done preferably in “complete darkness” and toward the northeast, for the Perseids. No special equipment is required.
The Perseids are much more visible in the northern hemisphere, because no meteor is visible below about 30 degrees south latitude. The best time is during the hours before dawn when the sky is darkest. It is sometimes possible to see the Perseid meteors during the peak of activity as early as 10 p.m., but the best time for observation is at 3 a.m., according to NASA.
Nevertheless, this year, unlike last year, the Perseid observation will meet a major obstacle, the Moon. There will be a full Moon and it will illuminate the whole sky.
In addition to the Perseids, there are many more meteor showers to observe each year. The Southern Delta Aquariids, usually active between July and August, can be best seen from the southern tropics. These are generally small meteors and are difficult to observe.
There are also alpha Capricornids, active from July to August. What is remarkable about this shower is the number of bright meteors produced during its period of activity, which was observed on both sides of the equator.
Then, this year, we will have to wait for the Orionids, between September 26 and November 22, 2022, with a peak of activity on the night of October 20 to 21. They are quite visible, despite a low density of shooting stars (10 to 20 per hour). These meteors come from Halley’s Comet.
