A small asteroid grazed near the Earth, a few hours after its discovery

A small asteroid grazed near the Earth

Astronomers at Mount Lemmon in Arizona discovered a car-sized asteroid yesterday (September 7, 2021). Quick calculations of its trajectory showed that it must have flown over our planet just hours after its discovery. According to NASA’s Center for Near Earth Object Studies (CNEOS), the closest approach to the asteroid occurred at 07:28 UTC (3:28 a.m. EDT) on September 8. The asteroid now bears the designation 2021 RS2. It is the closest space rock to pass through Earth so far in 2021. According to The Watchers website, it is the 81st known asteroid to have flown over Earth at a lunar distance since early 2021. .

Asteroid 2021 RS2 has come just 9,532 miles (15,340 km) from the Earth’s surface. Was it close? Yes, really close. The diameter of the Earth is approximately 7,917.5 miles (12,742 km). We can therefore say that the new space rock passed a little further than a terrestrial diameter.

The small asteroid was moving at 39,366 miles per hour (63.353 km / h) or 17.59 kilometers per second, relative to Earth.

But… this object is small. Its size is estimated to be only 11.5 feet (3.5 meters) in diameter. So he might have been taller than the tallest man on Earth, but he wasn’t big enough to put us on Earth in danger. If 2021 RS2 had had any closer to us, if it had entered Earth’s atmosphere, friction with the air would have caused this small asteroid to disintegrate. On the other hand, a space rock the size of 2021 RS2 would have caused a very impressive and shining meteor in our skies.

Why haven’t we seen it sooner?

Small asteroids like this are not easy to spot. They are particularly difficult to detect when they are located a certain distance from the Earth. As they get closer, we are more likely to spot them. It’s amazing that we can spot them all! A few decades ago, we couldn’t have done it. Larger asteroids, on the other hand, generally reflect sunlight more effectively. They can therefore be seen from further away and, often, weeks earlier. And the largest known asteroids, which are hundreds of kilometers in diameter, can be tracked continuously.

Astronomer KW Wierzchos (@WierzchosKacper on Twitter) made the 2021 RS2 discovery on September 7, using the 60-inch (1.52-meter) telescope at Mount Lemmon, Arizona.

Bottom line: The small 2021 RS2 asteroid grazed less than one Earth’s diameter from Earth on September 7, 2021. It passed within 10,000 miles (about 15,000 km).

Via NASA: 5 next asteroid approaches