Asteroid 2024 YR4 is a near-Earth asteroid, meaning it is an asteroid in an orbit that brings it into Earth’s region of the Solar System. 2024 YR4 is estimated to be about 130 to 300 feet (40 – 90 meters) wide and has a very small chance of Earth impact on Dec. 22, 2032.
This object is of particular interest for planetary defense for two reasons: 1) it is large enough to cause localized damage in the unlikely event that it should impact Earth, and 2) while 2024 YR4 has a very small chance of Earth impact in 2032, it has surpassed the 1% impact probability threshold to warrant formal notification of the object to other U.S. government agencies involved in planetary defense as well as to the Space Mission Planning Advisory Group and to the United Nations Office of Outer Space Affairs per the International Asteroid Warning Network’s notification charter.
As more observations of the asteroid’s orbit are obtained, its impact probability will become better known. It is possible that 2024 YR4 will be ruled out as an impact hazard, as has happened with many other objects that have previously appeared on the NASA JPL asteroid risk list. It is also possible its impact probability will continue to rise. The latest data will continue to be made available via NASA’s automated Sentry page. Updates will also continue to be posted on NASA’s planetary defense blog.
There was a period of 250 million years of mass extinctions on our Earth.
In 2010, we proposed that there was a period of 250 million years of mass extinctions on our earth—the”Extinction Clock.” During this period, 80% of mass extinctions occurred.
And the period of 250 million years of the mass extinctions was recorded by HeTu 4000 years ago.
See Dayong Cao, “Times of Mass Extinctions Drew The Cross And HeTu*” https://meetings.aps.org/Meeting/APR24/Session/OD01.9