The Virtual Telescope Project, based in Rome, Italy, captured the asteroid (99942) Apophis on March 2, 2021. The asteroid is shown as a dot – while the stars around it are shown as stripes – because the telescope followed the motion of the asteroid. It moves through space with respect to Earth at 4,658 km / sec (2,894 miles / sec). Image via Virtual Telescope.
Astronomers have turned their gaze to the asteroid Apophis this week, as it makes its closest passage to Earth before its very close passage to 2029. It will be closer in 2021 from March 5 to 6, no very especially close this time, but still within reach of ground-based telescopes and radar. Apophis is an asteroid close to Earth with a relatively large size (almost 400 meters in diameter). It sparked excitement in 2004 when early observations suggested it could attack Earth as it happened in 2029. A 2029 strike was later ruled out and Apophis is not expected to be able to attack Earth in this century. But this asteroid is a frequent visitor to our space region and astronomers want to know more.
The asteroid Apophis will sweep the closest to our planet on March 6, 2021 at 01:15 UTC (March 5 at 20:15 EST; translate UTC to your time). In this 2021 step, it will reach 16,852,369 km (10,471,577 miles). It is about 44 times the distance from the moon, a very safe distance for this step.
NASA’s Goldstone Deep Space Communications Complex in California has the asteroid on its observation calendar since March 3, 2021 and plans to continue observing it until March 14. Researchers at the West Bank Green Bank Telescope also began observing Apophis on March 3; Green Bank coordinates observations with Goldstone because using these two telescopes together allows the data to be sharper. Astronomers, of course, mourn the loss of the Arecibo telescope in Puerto Rico. On the street it is said that Arecibo, known for his asteroid radar observations, would have been the best telescope in the world to observe Apophis this year. Arecibo collapsed last fall, however, causing the telescope to shut down. The International Asteroid Warning Network (IAWN), which has members in Europe, Asia and South and North America, serves as a hub for the 2021 campaign to observe Apophis. Its coordinator is astronomer Vishnu Reddy, an expert in planetary defense at the University of Arizona.
The Virtual Telescope Project in Rome offers a free online viewing session of the asteroid Apophis from March 5 to 6, 2021. The feed will start on March 6 at 00:00 UTC (March 5 at 19:00 EST; translate UTC at your time).
Click here for more information on the live view of the Apophis asteroid in the Virtual Telescope from March 5 to 6, 2021.
Earlier observations with radar observations Goldstone and Arecibo confirmed that Apophis has an elongated shape. Image via NASA / JPL.
In addition, astronomers plan to study the asteroid Apophis using NASA’s NEOWISE infrared space telescope in April 2021. This is the same telescope that discovered the 2020 favorite comet, the NEOWISE comet, which has now been faded from view.
After the passage of 2029, the asteroid Apophis will also make remarkable steps close to Earth in 2036 and again in 2068. Land attacks in 2029 and 2036 have been ruled out. As of February 2021, the chances of impact during the Apophis overflight of 2068 are now 1 in 380,000. This is a 99.99974% chance that the asteroid will miss Earth in 2068.
Apophis observations in 2021 should further improve our knowledge of the shape and rotation of the asteroid and help reduce the uncertainties of the orbit of the space rock caused by the Yarkovsky acceleration.
In some cases, acceleration: a to change in the speed and direction of an object through space: it can help prevent collisions. Studies on Yarkovsky’s acceleration related to the asteroid Apophis suggest that this is the case for this asteroid. Preliminary calculations (done in 2016) were done all but ruled out the probability of an impact in 2068. The chance of an impact was seen in 2016 as very small, with only 1 in 150,000 chances of impact, or a 99.99933% chance that the asteroid missing on Earth.
The most recent observations, first discussed in October 2020 and updated again in early 2021, show a decreasing risk.
This is a Yarkovsky acceleration of the asteroid Apophis, detected by astronomers at the University of Hawaii, which has reduced the probability of impact of the 2068 overflight.
Bitbit of the asteroid Apophis (pink) in contrast to the Earth’s orbit (blue). The yellow dot represents the sun. Apophis takes 323.6 days to orbit the sun. The Earth takes 365.3 days. Therefore, this asteroid is a fairly frequent visitor to our space region. Image via Phoenix7777 / Wikimedia Commons.
Astronomer Dave Tholen and co-workers used the 323-inch (8.2-meter) Subaru telescope in Maunakea, Hawaii, to make the most recent observations. These astronomers were able to update the risk of impact on the Earth of Apophis, including the latest measurements of the Yarkovsky effect, which arises from a tiny thrust imparted by sunlight.
Visit the Apophis page at the Center for Near Earth Object Studies
The new work of Tholen and colleagues suggests that Apophis, with an estimated diameter of between 3.40 and 370 meters, is drifting more than 170 meters per year from its planned position in its orbit.
Tholen has been tracking Apophis’ movement in the sky since he and his colleagues discovered it at the Kitt Peak National Observatory near Tucson, Arizona on June 19, 2004. He said in a statement:
We have known for a long time that it cannot have an impact with the Earth during the approximate approach of 2029.
The new observations we got with the Subaru telescope [in 2020] they were good enough to reveal the Yarkovsky acceleration of Apophis, and show that the asteroid moves away from a purely gravitational orbit about 170 meters. [about 500 feet] per year, which is enough to keep the 2068 impact scenario at stake.
These observations are not easy to obtain and analyze. Factors such as the distance of the asteroid at the time of observation, its composition, shape and surface characteristics affect the result.
But astronomers are pushing to understand the orbit of the asteroid Apophis because of its next barrier on our planet in this century and beyond.
Read more about the Yarkovsky effect: pushing asteroids with sunlight
Of course, Apophis is not the only asteroid close to Earth. In recent years, astronomers have been able to find and track many tiny asteroids that swept close to Earth. For example, on September 24, 2020, the asteroid 2020 SW swept even closer to us than our meteorological and television satellites, as well as other geostationary satellites, orbiting our planet at about 35,900 km from the Earth’s surface. The asteroid 2020 SW was located at approximately 7% of the Earth-Moon distance. But it is estimated that the asteroid 2020 SW has only a diameter of about 14 to 32 feet (about 4.5 to 10 meters). This is very small in contrast to the asteroid Apophis.
This animation shows the distance between the asteroid Apophis and Earth at the time of the closest approach to the asteroid in 2029. The blue dots are artificial satellites orbiting our planet and the pink represents the International Space Station. Image via NASA / JPL-Caltech.
The 2029 passage of the asteroid Apophis. On April 13, 2029, Apophis ’encounter with Earth will be very close. At most, in 2029, Apophis will sweep only 37,725 km from our planet, or about 10% of the Earth-Moon distance. This is very close for a space rock over 3.40 meters wide. Lance Benner of NASA / JPL commented:
This will be the closest approach to something so big that is currently known. (In 2029) Apophis will be visible to the naked eye for several hours, and the tides on Earth will likely change their state of rotation.
Friday, April 13, 2029 will be a spectacle for the asteroid Apophis, both for the general public and for astronomers. Apophis will get so close that it will be visible only to the unassisted eyes; which almost never happens with asteroids. According to NASA, Apophis will first become visible in the southern hemisphere and will look like some light moving through Australia during this upcoming encounter. It will be over the Atlantic Ocean at the closest point to Earth. It will move so fast that it will cross the Atlantic in just one hour and will have crossed the United States in the afternoon / evening in the next hour. Calculations indicate that Apophis will reach a visual magnitude of 3.1 during this approach, comparable to the Little Bear stars. By 2029, Apophis is expected to be visible to the naked eye from parts of Australia, Western Asia, Africa and Europe.
Like many other asteroids, Apophis has been classified as a potentially dangerous asteroid by the Center for Smaller Planets of the International Astronomical Union. This only means that it is an asteroid whose orbit sometimes brings it closer to Earth, which is large enough to cause “significant regional damage” in the event of an impact. A survey by the NEOWISE spacecraft in 2012 suggested that there are 4,700 ± 1,500 potentially dangerous asteroids with a diameter greater than 100 meters.
According to some estimates, an asteroid the size of Apophis can be expected to impact the Earth every 80,000 years.
As a result of the close approximation of April 2029, perturbations caused by Earth’s gravity are expected to change the orbit of Apophis from the Aten class to the Apollo class. Image via NASA / JPL.
In short: the asteroid Apophis has passed through Earth this week the closest before its very close passage in 2029. This March 5-6, 2021, the passage will be 44 times farther than the moon’s orbit . Apophis is a relatively large body, notable for its extremely close approximations to Earth in 2029, 2036, and 2068. Astronomers’ observations indicate that Apophis is extremely unlikely to reach Earth this century.
Read more about the Yarkovsky effect: pushing asteroids with sunlight
Via CNEOS
