Monday, May 14, 2012

Near Earth Object (NEO), Asteroid 2010 KK37. May 19, 2012

The next Near Earth Object (NEO) is Asteroid 2010 KK37.  Rumor has it that there is some worry about how close it will come.  However, from what I can find by scanning the Internet, there is nothing to worry about.  I guess we'll just have to wait and see.  Here is what I found...

The 19 - 43 metre wide asteroid 2010 KK37 will make a close pass (2.3 lunar distances, 0.0058 AU), travelling at 10.94 km/second, to the Earth-Moon system on the 19th May, 2012 @ 10:36 UT ±1 day 03:50.



the above video poster says-

Published on Apr 24, 2012 by 
The 19 - 43 metre wide asteroid 2010 KK37 will make a close pass (2.3 lunar distances, 0.0058 AU), travelling at 10.94 km/second, to the Earth-Moon system on the 19th May, 2012

The asteroid was discovered by the Mt. Lemmon Survey on the 23rd May, 2010.




Bill gave the link to the data for 2010 KK37 on JPL's HORIZONS system…

If you look at the encounter data for 2012-May-19 you'll see that the uncertainty in the time of closest approach to the Earth is 1 day 3 hours 50 minutes, which is to say quite a lot.

The nominal distance is 0.0058 AU (about 870,000 km) but the minimum range is given as 0.00041 AU (only about 62,000 km from the centre of the Earth) while the maximum range is 0.036 AU (about 5.4 million km). The semi-major axis of the uncertainty ellipse is just over 1 million km.

Now you might ask why, if the nominal distance is 870,000 km and the semi-major axis of the uncertainty ellipse is 1 million km, isn't an impact considered a possibility? Doesn't the uncertainty ellipse include the Earth? Well the answer lies in the fact that the uncertainty ellipse is usually very narrow with its major axis in the along track direction. In this case the semi-minor axis is only 4 km wide. Couple that with the fact that the angle between the Line of Variations (LOV, the long axis of the ellipse) and the range vector (the direction to the centre of the Earth) at the nominal closest approach is 4.3 degrees (see column labelled 'range-LOV angle' in the table) results in the line of variations missing the Earth entirely.

You can construct a triangle. Draw a long line. This is the line of variations. Put a small dot in the middle of the line. This is the asteroid. Draw a small-ish circle a bit to the side of the line some distance from the dot. This is the Earth. Draw a line from the dot to the centre of the circle. This is the range vector. Draw another line from the centre of the circle to make a right angle with the long line of variations. This is the closest perpendicular distance from the LOV to the Earth. You now have a right triangle. The small angle between the range and the LOV is 4.3 degrees. The range is the hypotenuse and is the nominal approach distance, 
0.0058 AU. The short perpendicular distance from Earth to the LOV is thus 0.0058 sin 4.3 = 0.0004 AU. Thus the uncertainty ellipse does stretch either side of the Earth but it passes to one side (or above or below depending on your point of view) of the Earth and thus no impact is possible.

2010 KK37 is only about 40 degrees from the Sun in the sky at present and remains so right up until the close pass so we don't have any chance of seeing it again until the day of the passage. I hope the survey telescopes manage to pick it up again and nail down its orbit.


2012 HA34
May 2
2.9 LD
38 m
2010 KK37
May 19
2.3 LD
31 m
4183 Cuno
May 20
47.4 LD
5.7 km
2002 VX94
May 26
72.8 LD
1.1 km
2002 AC
Jun 16
62.2 LD
1.2 km
1999 BJ8
Jun 16
68.8 LD
1.1 km
2005 GO21
Jun 21
17.1 LD
2.2 km
2003 KU2
Jul 15
40.3 LD
1.3 km
2004 EW9
Jul 16
46.8 LD
2.1 km
2002 AM31
Jul 22
13.7 LD
1.0 km
Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.

Lunar Distance

by FRASER CAIN on DECEMBER 30, 2009Lunar Distance
Neil Armstrong on the moon. Really. Credit: NASA/ Andrew Chaikin

The average lunar distance is 384,399 km or 238,854 miles. That’s about the distance that light can travel in a single second.
I said that this number is an average, though. That’s because the Moon travels in an elliptical orbit around the Sun. When it’s at its closest point, called perigee, the Moon is only 363,104 km or 225,633 miles. And then at its most distant point, called apogee, the Moon gets out to 405,696 km or 252,088 miles.
That’s a pretty big difference in lunar distance over the course of the Moon’s orbit, and we can see this from here on Earth. When the Moon is at the closest point in its orbit, it appears about 15% bigger. And when the closest moon coincides with a full Moon, it can be 30% brighter than a smaller full moon.
You might be surprised to know that scientists can actually measure the lunar distance within just a few centimeters. That’s because the Apollo astronauts placed small reflective mirrors on the surface of the Moon during the 60s and 70s. Scientists shoot laser beams at the Moon and time how long it takes for them to return. From this they can calculate the distance to the Moon.
They’ve also discovered that the Moon is slowly drifting away from the Earth at the rate of about a centimeter a year. But don’t worry, the Moon won’t escape into space any time soon. We’ll actually be destroyed by the Sun when it becomes a red giant in about 7 billion years before the Moon gets that far away from us.

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