Asteroid 2021 SG came from the direction of the sun

Asteroid 2021 SG: bigger than Chelyabinsk

The new 2021 SG asteroid is about four times the size of the 17-meter (18-meter) space rock that disintegrated above Chelyabinsk, Russia on February 15, 2013. The Chelyabinsk meteor created a wave of shock that shattered the windows of six Russian cities. . This prompted some 1,500 people to seek medical attention, mainly because of the shards of glass. But the newly found asteroid 2021 SG did not hit. It just passed very close, only about half the distance from Earth to the Moon, last week. Astronomers finally recovered the asteroid – discovering it for the first time – a day later, on September 17, 2021. They were using a large telescope, the 48-inch (1.2 meter) telescope at Mount Palomar in California. Why didn’t they spot him sooner? Because it was coming from the direction of the sun.

An analysis of its orbit indicates that asteroid 2021 SG was closest to Earth on September 16 at 8:28 p.m. UTC (4:28 p.m. ET).

Asteroid 2021 SG has an estimated diameter of 42 to 94 meters (138-308 feet). Its average diameter is 68 meters (223 feet). This contrasts with the 17 meters of the Chelyabinsk meteor before it entered Earth’s atmosphere.

It was coming from the direction of the sun. These words may sound scary to you. And they do it too – perhaps more so – to scientists working to detect near-Earth asteroids, in an effort to protect our planet. The Chelyabinsk meteor that did so much damage and caused so much consternation in 2013 also came, unexpectedly, from the direction of the sun. The point is, astronomers have become very good at detecting near-Earth asteroids. And there are programs in place to monitor them. Some observatories are constantly taking images of the night sky in search of new asteroids. And astronomers think they’ve got a handle on all potentially dangerous asteroids… except those that might come from the direction of the sun.

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If it entered our atmosphere, an asteroid as large as 2021 SG would produce a huge, very impressive meteor. Asteroid 2021 SG isn’t just big. It is also a fast moving asteroid, traveling through space at the incredible speed of 53,281 miles per hour (85,748 km / h or 23.8 km per second), relative to Earth. On the closest approach on September 16, 2021, asteroid 2021 SG came closest to Canada and Greenland.

The 2021 SG orbit shows that it is an Apollo-type asteroid that revolves or orbit the sun every 27 months (2.24 years). This time it passed Earth just after passing Mercury’s orbit.

Asteroids in the direction of the sun

Can do astronomers detect asteroids coming from the direction of the sun?

Right now, no, they can’t. But astronomers will soon have a new tool to detect many space rocks, including those lurking in the glare of the sun. NASA is developing a new infrared space telescope called the Near-Earth Object Surveyor, or NEO Surveyor, space telescope. NASA expects this telescope to find 90% of near-Earth objects with a diameter of 140 meters or more. An impact from such a large object could level a city. This telescope – scheduled for launch in 2026 – is said to have spotted both the Chelyabinsk space rock and 2021 SG. It should improve our planetary defense.

Meanwhile, scientists now believe that a Chelyabinsk-like event could occur more frequently than previously thought. For example, another good-sized space rock passed through Earth in 2015. 2015 TB45 was roughly the same size as 2021 SG. Its diameter was approximately 2,000 feet (610 meters). He passed a little further, just outside the orbit of the moon. Yet in the vastness of our solar system… it’s pretty close. Astronomers spotted it three weeks before the closest approach to October 31, 2015. Some radar images coincidentally showed a space rock shaped like a skull. And so some have dubbed it the Halloween asteroid.

What does all this mean? Perhaps – even with observing astronomers – an impressive asteroid event is currently possible without warning, at any time. This would be true if the object was coming from the direction of the sun. But in a few years, we should all have additional protection from the new NEO Surveyor. And this fact should help us all – including astronomers – to feel more secure!

Bottom line: Asteroid 2021 SG – roughly four times the diameter of the 2013 Chelyabinsk meteor – made a close-to-Earth pass on September 16, 2021, without being detected before.