Headline Graphic for 2005 YU55
On Tuesday November 8th, 2011 asteroid 2005 YU55 which is about the size of an aircraft carrier buzzed the Earth within 201,700 miles (324,600 kilometers). As a point of reference, our moon is 238,000 miles away! Even though asteroids of this size pass by Earth frequently, the last time a space rock this large came as close to Earth was in 1976, although astronomers did not know about the flyby at the time. The next such close flyby will take place in 2028, when an asteroid called 2001 WN5 will pass about halfway between the Moon and Earth.
The path of Asteroid 2005 YU55, when it was visible in the skies above North America, took it thru the constellation of Pegasus. Although there was an almost full moon washing out the sky, conditions were clear.
Path of 2005 YU55 on Nov 8th & 9th, 2011 – From S&T
Several Raleigh Astronomy Club members attempted to capture a view of this asteroid either visually or via a camera.
RAC member Mark Lang had posted the following on the RAC web site gallery. If you look closely at this animation, you will see two moving objects. The object in the upper center is the mystery object, maybe a tumbling rocket booster, and in the bottom left corner is near earth asteroid 2005 YU55. This sequence was taken about 1:37 UT on Nov. 9, 2011. The bright star in the field is SAO 107262 in Pegasus. For about two weeks, I thought the brighter object was the asteroid until talking with some other imagers who also got fooled. This was taken with my 4″ Genesis refractor and my SBIG ST-402 camera unguided. The animation is a 9 frame sequence of 3 seconds and a one second gap between frames. North is to the right and west is at the bottom of the frame.
(Link Has Been Removed)
Another member, Mike Keefe, captured the asteroid visually from the club’s viewing site near Jordan Lake. Mike posted the following to the club’s email distribution list. I was finally able to track this sucker down at around 9:35 when it flew thru an asterism of a backwards 7, this was one of the intercept points I had calculated.
Intercept point for 2005 YU55
There were times I could make out the asteroid very clearly in my 8″ and others when I had to use averted vision. I thought it could have been the seeing causing this variability but then noticed the surrounding stars of similar brightness were not fading, so it must have been varying in brightness (the asteroid’s rotation perhaps?). The asteroid was moving quite fast thru my field of view. It took perhaps a minute to move from edge to edge in my eyepiece, which is about 3/4 of a degree (or 42’). I tracked it visually until almost 11:45pm, occasionally losing it and having to calculate new intercept plots based on the data points gathered from the IAU Minor Planet Center.
This was my first time observing an asteroid; half the fun was the hunt!
This was truly a great observing opportunity!
