The Virtual Telescope Project, based in Rome, Italy, captured the asteroid (99942) Apophis on March 2, 2021. The asteroid appears as a dot – while the stars around it appear as stripes – because the telescope followed the movement of the asteroid . It moves through space relative to the earth at 4,658 km / sec (2,894 miles / sec.). Image via virtual telescope.
Astronomers this week turned their attention to the asteroid Apophis, as it makes its closest past Earth before coming very close to the 2029 Pass. It comes closest in 2021 on March 5-6, not very close this time, but still within reach of terrestrial telescopes and radar. Apophis is a near-Earth asteroid of relatively large size (almost 400 meters). It sparked excitement in 2004 when early observations suggested it could hit the earth if it passed in 2029. A 2029 strike was subsequently ruled out, and Apophis is not expected to hit the earth in this century. But this asteroid is a regular visitor to our space, and astronomers want to know more.
Asteroid Apophis will sweep closest to our planet on March 6, 2021 at 01:15 UTC (March 5 at 20:15 EST; translate UTC to your time). At this pass of 2021, it will be within 16,852,369 km. It’s about 44 times the moon’s distance, a very safe distance for this pass.
NASA’s Goldstone Deep Space Communications Complex in California has been compiling the asteroid on its observation schedule since March 3, 2021, and plans to continue it until March 14. Researchers at the Green Bank Telescope in West Virginia also began observing Apophis on March 3; Green Bank coordinates observations with Goldstone because using these two telescopes together can sharpen the data. Astronomers, of course, mourn the loss of the Arecibo telescope in Puerto Rico. The news on the street is that Arecibo – known for its radar observations of asteroids – would have been the world’s best telescope to observe Apophis this year. Last fall, however, Arecibo collapsed, causing the telescope to be shut down. The International Asteroid Warning Network (IAWN) – which has members in Europe, Asia and South and North America – serves as a clearing house for the 2021 campaign to observe Apophis. Its coordinator is astronomer Vishnu Reddy, an expert in the field of defense at the University of Arizona.
The Virtual Telescope Project in Rome is hosting a free online viewing session of asteroid Apophis on March 5-6, 2021. The feed starts on March 6 at 00:00 UTC (March 5 at 19:00 EST; translate UTC to your time).
Click here for more information on Virtual Telescope’s sighting of asteroid Apophis on 5-6 March 2021.
Earlier observations with Goldstone and Arecibo radar observations have confirmed that Apophis is elongated in shape. Image via NASA / JPL.
In addition, astronomers plan to study asteroid Apophis using NASA’s NEOWISE infrared space telescope in April 2021. It is the same telescope that discovered the favorite comet of 2020, Comet NEOWISE, which has now disappeared from view.
After the pass of 2029, asteroid Apophis will also make significant passages in 2036 and again in 2068. Earthquakes in 2029 and 2036 are excluded. As of February 2021, the chance of impact during Ap68s in 2068 is now 1 in 380,000. There is a 99.99974% chance that the asteroid will miss Earth in 2068.
The observations of Apophis in 2021 should further improve our knowledge of the shape and rotation of the asteroid, and this will help reduce uncertainties in the orbit of space, caused by the Yarkovsky acceleration.
In some cases, acceleration – a alter in an object’s speed and direction through space – can help prevent a collision. Studies of the Yarkovsky acceleration in relation to asteroid Apophis suggest that this is the case for this asteroid. Previous calculations (made in 2016) have anything but excluded the likelihood of an impact in 2068. The chance of an impact in 2016 was seen as vanishingly small, with only 1 in 150,000 chances, or a 99.99933% chance that the asteroid would miss Earth.
The more recent observations, which were first discussed in October 2020 and updated again in early 2021, show a decrease risk.
It is a Yarkovsky acceleration of asteroid Apophis – detected by astronomers at the University of Hawaii – that reduced the impact probability for the 2068 flight.
Orbit of asteroid Apophis (pink) as opposed to the orbit of the earth (blue). The yellow dot represents the sun. Apophis takes 323.6 days to orbit the sun. The earth takes 365.3 days. This asteroid is therefore a fairly regular visitor in our space. Image via Phoenix7777 / Wikimedia Commons.
Astronomer Dave Tholen and co-workers used the 323-inch (8.2-meter) Subaru telescope at Maunakea, Hawaii, to make the latest observations. These astronomers were then able to update Apophis’ Earth impact risk, including the latest measurements of the Yarkovski effect, resulting from a small pressure given by sunlight.
Visit the Apophis page at the Center for Near Earth Object Studies
The new work of Tholen and colleagues suggests that Apophis – whose estimated diameter is between 1140 and 1114 feet (340 to 370 meters) – drifts more than 500 feet (about 170 meters) per year from its expected position in its orbit.
Tholen has been monitoring the movement of Apophis in the air since he and his colleagues discovered it on June 19, 2004 at the Kitt Peak National Observatory near Tucson, Arizona. He said in the statement:
We have known for some time that an impact on Earth is not possible during the 2029 close approach.
The new observations we got with the Subaru telescope [in 2020] was good enough to reveal the Yarkovsky acceleration of Apophis, and they show that the asteroid drifts about 170 meters away from a pure gravitational orbit. [about 500 feet] per year, which is enough to keep the 2068 impact scenario in play.
These observations are not readily available and can be analyzed. Factors such as the distance of the asteroid during its observation, its composition, its shape and its surface characteristics affect everything.
But astronomers insist on understanding the orbit of the asteroid Apophis because of the close livestock on our planet in this century and beyond.
Read more about the Yarkovsky effect: pushing asteroids around with sunlight
Apophis, of course, is not the only asteroid near Earth. In recent years, astronomers have been able to find many small asteroids that are washing close to Earth. For example, on September 24, 2020, asteroid 2020 SW swept even closer to us than our meteorological and television satellites as well as other geostationary satellites, orbiting our planet about 35,900 km from the earth’s surface. Asteroid 2020 SW has reached about 7% of the Earth’s lunar distance. But the asteroid 2020 SW is estimated to be only about 4.5 to 10 meters in diameter. It is very small in contrast to the asteroid Apophis.
This animation shows the distance between the Apophis asteroid and Earth at the time of the closest approach to the asteroid in 2029. The blue dots are man-made satellites orbiting our planet, and the pink one represents the International Space Station. Image via NASA / JPL-Caltech.
The 2029 Pass of the Asteroid Apophis. The encounter of Apophis with Earth on April 13, 2029 will be very close. At its closest in 2029, Apophis will sweep just 37,725 km from our planet, or about 10% of the Earth’s lunar distance. It is very close for a space rock of more than 340 meters! Lance Benner of NASA / JPL said:
This is the closest approach by something this great is currently known for. (In 2029) Apophis will be visible to the naked eye for several hours, and the tides of the earth will probably change its state of rotation.
On Friday, April 13, 2029, the asteroid Apophis will be a spectacle for the general public and astronomers. Apophis will come so close that it is visible to the naked eye only; something that almost never happens to asteroids. According to NASA, Apophis will first become visible in the Southern Hemisphere and will look like a spot of light moving through Australia during this close encounter. It will be across the Atlantic Ocean at its closest approach to Earth. It will move so fast that it will cross the Atlantic Ocean within an hour and cross the USA within the next hour in the late afternoon / early evening. Calculations indicate that Apophis will reach a visual magnitude of 3.1 during this approach, comparable to the stars in the Little Dipper. By 2029, Apophis is expected to be visible to the naked eye from some areas of Australia, West Asia, Africa and Europe.
Like many other asteroids, Apophis was classified by the Minor Planet Center of the International Astronomical Union as a potentially dangerous asteroid. It only means that it is an asteroid whose orbit sometimes brings it close 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 of more than 100 meters.
According to some estimates, an asteroid the size of Apophis can be expected to hit the earth about every 80,000 years.
Due to the extremely close approach of April 2029, disturbances caused by the Earth’s gravity are expected to change the orbit of Apophis from the Athens to the Apollo class. Image via NASA / JPL.
In short: Asteroid Apophis’ orbit around the earth this week will be the closest before its extraordinarily close pass in 2029. This pass from 5-6 March 2021 will be 44 times beyond the orbit of the moon. Apophis is a relatively large body, notable for its extremely close approach to Earth in 2029, 2036, and 2068. The observations of astronomers indicate that Apophis is highly unlikely to hit Earth this century.
Read more about the Yarkovsky effect: pushing asteroids around with sunlight
Via CNEOS
