A close encounter with an asteroid

Radar image of asteroid 2005 YU55

At this precise moment, 11:28pm UK time, asteroid 2005 YU55 is passing just 201,700 miles (324,600 kilometers) from the Earth, its closest approach for at least the last 200 years. [1]

It’s travelling at a speed of 30,680 miles (49,370 kilometres) per hour, which is 8.523 miles (13.71 kilometers) every second! [2] [3]

The Clay Center Observatory in Brookline, Massachusetts, is broadcasting a live video from their 25-inch telescope (see their Facebook post).  The Keck Observatory in Hawaii is also broadcasting a live video, available here and here (see their Facebook posts).

The asteroid is closer than the Moon, as can be seen in the diagrams below:

Diagram of asteroid 2005 YU55's flypast of the Earth and Moon

The upper diagram is looking straight down on the ecliptic plane, and the lower diagram is looking edge-on to the plane. [4]

2005 YU55 is a C-type asteroid, nearly spherical, 400 metres in diameter, and “darker than charcoal at optical wavelengths”. [4] [5]  Its name indicates that it was the 1395th minor planet (“U55”) discovered between 16 and 31 December (“Y”) in 2005. [6]

Although classified as a potentially hazardous object, 2005 YU55 poses no threat of an Earth collision over at least the next 100 years.  However, this will be the closest approach to date by an object this large that we know about in advance and an event of this type will not happen again until 2028 when asteroid (153814) 2001 WN5 will pass to within 0.6 lunar distances. [4]

NASA has a couple of interesting videos about the asteroid here and here, and a longer broadcast here.


The Keck Observatory’s broadcast is now available to watch again, and a short clip is available here.

Asteroid 2005 YU55 at its closest point to Earth

The image above was captured from Clay Center’s broadcast at 11:28pm (by Lights in the Dark).  A couple of real-time clips from that broadcast are available here and here, and some timelapse videos are available here, here and here.

2 responses to “A close encounter with an asteroid

  1. Hey you got a nice blog. mine is about pace news

  2. correction-

    Hey you got a nice blog. mine is about space news

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