No, a kilometre-wide asteroid isn't 'skimming past' us today
The path of asteroid 1999 FN53 at closest approach on May 14, 2015. Credit: NASA/JPL-Caltech
Meteorologist/Science Writer
Thursday, May 14, 2015, 9:19 AM - The internet rumour mill is at it again, speaking of a "narrow miss" by a kilometre-wide asteroid that will supposedly "pass close," "brush close" or "skim past" the Earth on Thursday, May 14. For anyone concerned about this, rest assured that NASA has the real details on this space rock and they'll be learning even more during this flyby.
The asteroid in question is one that NASA and astronomers have known about for over 16 years - asteroid 1999 FN53.
On Thursday, May 14, at 7:25 a.m. Eastern Time, this space rock - estimated at between 600-1300 metres wide - is making its closest approach to the Earth since 1999, which is also its closest approach until the year 2134. However, this asteroid is of no threat to Earth.
"Closest," but not "close"
May 14, 2015 may be the date of 1999 FN53's latest closest approach, but any mention of this asteroid being "close" or "skimming past" is highly subjective.
Compare its distance to the diameter of the solar system, and it's flying past Earth at 0.2 per cent of the orbital distance of Neptune (9 billion km away), or 0.0001 per cent of the distance to the outer edge of the Oort cloud (7.5 trillion km away).
Consider, instead, the span of distance between the Earth and the Sun - one astronomical unit or around 150 million kilometers - and at 7:25 a.m. ET on Thursday, it flew past at less than 10 per cent of that span.
In any of those cases, the result is a fairly small number, which may raise some concern. However, compare its distance to something a bit more practical, and meaningful, such as the distance between the Earth and the Moon - 384,400 km - and it's not even close.
As 1999 FN53 comes closest to Earth today, it will be a total of 10 million kilometres away, or around 26 times further away than the Moon.
To sum up, according to NASA's Jet Propulsion Laboratory:
1999 FN53 is NOT classified as "Potentially Hazardous" because the asteroid does not approach within 0.050 au (7.5 million km) of Earth.
That's just considering the category of "potentially hazardous," which is a list reserved for asteroids that could, maybe, someday become a worry for us. Despite its size, which would certainly present us with a problem if it were to hit Earth, 1999 FN53 doesn't even rate a position on that list.
The #asteroid 1999 FN53 will safely pass by the Earth on May 14. It poses no threat. https://t.co/d2yvBbxkos pic.twitter.com/4oZfnrmINt
— NASA Solar System (@NASASolarSystem) May 14, 2015
Scanning target
Even though this asteroid is no threat to Earth, it is of interest to scientists here.
According to NASA, the NEOWISE satellite made observations of it in mid-April, producing an estimated diameter of around 600 metres. Further scans this week, using radar signals from the Arecibo radio telescope in Puerto Rico, refined that estimate to closer to 900 metres. The radio dish network at Goldstone, in California, has also joined in on the observation program, to help gather as much information about 1999 FN53 flies as possible.
These observations will help scientists to understand more about these objects - their size, composition and density, speed and rotation, and even other details (does it have companions or moons?). This is all useful for the basic science of near-Earth asteroids, but it's also useful information for those interested in planetary defense.
