Incoming! Another asteroid to skim by

A newly discovered asteroid will miss the Earth by only 7,500 miles on Monday – coming 32 times closer than the moon. The space rock, which could be the size of a large house, will become bright enough to be seen in stargazers’ small telescopes when nearest.

Asteroid 2011 MD imaged by Peter Birtwhistle
Asteroid 2011 MD imaged by Peter Birtwhistle (Galaxy Picture Library)

It was only spotted yesterday, 22 June, by LINEAR, a pair of robotic telescopes in New Mexico that scan the skies for such hazards.

The latest predictions, according to show a closer approach than the 11,000 miles originally stated, and so our report has been updated. However, there is still no danger of the asteroid striking the Earth, although gravity will slightly alter its trajectory and it will fly into the zone inhabited by high-flying communications and TV satellites.

One of the observers who subsequently confirmed the intruder was UK observer Peter Birtwhistle, with a photo taken from Great Shefford, near Hungerford, Berks.

It will be daylight in the UK when the asteroid, which has been named 2011 MD, makes its close encounter over the southern hemisphere. But astronomers in other parts of the world, such as South America, will be able to watch it brighten and fade rapidly as it speeds through the starry background.

Peter, 53, has discovered dozens of asteroids himself from his UK observatory. in 2005 he was awarded a £4,500 international prize for helping protect the Earth from an asteroid strike.

Asteroid 2011 MD is estimated to be between 10 yards and 50 yards wide. UK asteroid expert Dr Emily Baldwin, of Astronomy Now magazine, told Skymania News: “We are certain that it will miss us, but if it did enter the atmosphere, an asteroid this size would mostly burn up in a brilliant fireball, possibly scattering a few meteorites.”

In February, asteroid 2011 CQ1, the size of an armchair, missed Earth by just 3,405 miles, the closest ever recorded near miss. (NB, “Stella”, who is one of the UK’s leading satellite experts and a professional astronomer, reminds us in the comments of a spectacular fireball over Utah in the USA in 1972 when a meteoroid entered the atmosphere at such a velocity and shallow angle that it left the atmosphere again and continued to orbit the Sun! There is a spectacular photo of this here.)

Astronomers are also looking at the possibility that the “asteroid” might be the discarded rocket booster of a planetary probe launched many years ago because it is travelling in an orbit that is very similar to that of the Earth. If so, it reminds us of the case of a space probe called Rosetta being mistaken for an asteroid when it was on a scheduled approach in 2007. And a chunk of a Russian Proton rocket was identified as an asteroid only a year ago. (Update: The possibility of 2011 MD being a rocket appears to have been ruled out as further analysis if its orbit shows it has not been close to Earth during the years of the Space Age.)

On November 8, a 400-meter wide asteroid weighing 50 million tons, called 2005 YU55, will fly inside the orbit of the moon.

Asteroid 2011 MD's approach
Asteroid 2011 MD's approach (Click to animate)

Update (27 June): Above is an animation prepared by Skymania News from images taken by UK astronomer Nick Howes, of Wiltshire, collaborating with E. Guido and G. Sostero, using the Faulkes Telescope South robotic instrument at Siding Spring, New South Wales, Australia, today, just hours before closest approach. It was moving so fast at 12,000 mph (19,000 kph) that it appeared as a streak in individual exposures lasting just a few seconds! There is also a remarkable video, below, made by astronomers at the Črni Vrh Observatory in Western Slovenia of the asteroid racing across the sky as it was approaching Earth on 26 June.

Reporter: Paul Sutherland

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By Paul Sutherland

Paul Sutherland has been a professional journalist for nearly 40 years. He writes regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy, plus he has authored three books on astronomy and contributed to others.

5 thoughts on “Incoming! Another asteroid to skim by

  • 06/23/2011 at 6:20 pm

    “closest ever recorded near miss”

    how about Grand Teton from august 1972 at just 58 km?

  • 06/24/2011 at 8:13 am

    An interesting point, Stella, which I have addressed in the updated story. I suppose it all depends on how one blurs the distinction between an asteroid and a meteoroid, At the end of the day they are all fragments of cosmic crud!

  • 06/24/2011 at 8:22 am

    This latest visitor 2011 MD is likely to be a man-made object, probably a large rocket,
    that launched a planetary probe around a quarter-century ago. Further observations
    are needed to determine its true nature.

  • 06/27/2011 at 12:44 am

    Wow!!! Leaves me speechless…

  • Pingback: Asteroid to pass Earth closer than the Moon today – | Ilim

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