Since I mentioned asteroid 2024 YR4, the web coverage (note I didn’t say press coverage) is not encouraging. Not encouraging… about the state of the web. Scaremonger sites are, unfortunately, ready and willing to use scare fodder wherever they can find it.
Short Answer: the object is not even a PHA (potentially hazardous asteroid). PHAs are defined as having a MOID (Minimum Orbit Intersect Distance)- their “closeness”- and an absolute magnitude (their brightness- a measure of their size). PHAs are defined as having MOID=0.05 AU or less, and a maximum magnitude of H=22.0; asteroid 2024 YR4 has a magnitude of 24.
Long Answer: A magnitude of H=24 is smaller than the definition of a PHA (lower numbers are brighter and bigger). 2024 YR4 is too dim, therefore, too small to be a serious risk. The size estimate is roughly 40-90 meters wide, big enough to reach the ground, yet not enough to cause serious damage over more than a few kilometers’ radius. There is still some leeway on that radius, naturally. The object could be a carbonaceous chondrite, which would be very weak and mostly destroyed upon entering our atmosphere. Or it could be an iron meteor, which is strong and will reach the ground largely in one piece. We’re trying to study YR4 further, and narrow down the ranges on these stats. At this moment, it appears (as best we can tell) a common, stony type, in between carbonaceous and iron.
The asteroid 2024 YR4 is in the nighttime (not daytime) sky, and will continue to recede from Earth along its orbit without going into twilight. We will continue to track it for another month or two, improving our track on it, until it becomes just too far and dim to see. We’re already using telescopes of multi-meter aperture; as we go out to March or maybe April, it will take larger and larger telescopes (like, 6-8 meters) just to see it at all. Using the data from February 19-20, impact probabilities for the 2032 Earth pass have now declined, and will likely continue declining.
And yet, web sites claim the risk of 2024 YR4 has “doubled.” DOUBLED! What a misdirect- the impact probability (a separate figure from the damage estimate) during the 2032 Earth approach went from 1.3 percent to 2-3%. Wow, that’s such an increase! In reality, the total risk (impact odds, together with impact effect) was very low, and went to …still very low. Let’s see if those same sites will now print that impact odds have peaked, and are now falling.
Before you, the reader, panic, I suggest you learn. Learn about small-body astronomy, and learn about scare/troll/clickbait sites among our modern media. These sites are paid by the click, and try to get you looking at ads; that doesn’t work if you dismiss the page as full of nonsense, and barely read it. (Or don’t even click to it at all.) Unfortunately, these site operators prey upon- and profit from- an uneducated public, unable to spot clickbait and distinguish it from serious coverage. Are you clickbait prey?