Asteroid 2011 MD Flyby Update

Watch 2011 MD zip through the starfield in this series of exposures made this evening June 26 by Italian observers Rolando Ligustri and D. Da Rio starting at 10:16 p.m. local time. A picture was taken every 20 seconds.

There’s been continuing interest in this little asteroid that will fly some 7,500 miles from Earth around noon CDT tomorrow June 27 (updated time). First, no one’s in danger. Even if it did somehow strike Earth’s atmosphere, it would disintegrate into pieces and not cause harm. Second, for most locations it will be extremely faint.

Observers in Australia and New Zealand will have the best view, but even they’ll need a telescope. At brightest, 2011 MD will be 100 times fainter than the faintest star typically visible with the naked eye from a rural location or about magnitude 11.5. Here in the mid-section of the U.S., it will climb to a wimpy magnitude 14.6 before dawn interferes. Hawaiians will see it a magnitude brighter.

The Goldstone DSS-13 radio telescope will ping the asteroid with radio waves for a 5.5 hour time period today and examine the returned echoes to make a picture of 2011 MD and study its surface properties.

Earth's gravity reworked the orbit of asteroid 2011 CQ1 during its close flyby last February. Credit: NASA/JPL

At closest approach, 2011 MD will be traveling at about 4 miles per second. Close approaches by near-Earth asteroids aren’t uncommon. The closest to date was on February 4 this year when 3-foot-long 2011 CQ1 came within 3,400 miles of the Earth’s surface. That was close enough that Earth’s gravity reset the asteroid’s orbit. It came in one way and got ‘bent’ out another. The same will happen with 2011 MD as it swings round and departs the Earth’s vicinity.

Every newly-found asteroid gets a provisional name based on the year of discovery, the half-month in which it was discovered and the order of discovery within that half month. The first letter in its name represents the half-month. For example, the letter “A” applies to any asteroid found in the first half of January, the letter “B” the second half. The letter ‘I’ is not used. Since the last half of December is ‘Y’, the letter ‘Z’ can’t be a first letter, but can be a second letter when a 26th asteroid is discovered in a two-week period.

For example, an asteroid discovered on March 20 would start with “F”. 2011 MD was found in the second half of June, so its first letter is “M”. The second letter indicates the order of discovery. “D” is the 4th letter of the alphabet, so 2011 MD would be the 4th asteroid discovered in the second half of June 2011. In addition, there are subscripts when more than 25 asteroids are discovered over a 2-week period. A hypothetical 2011 MD1 would be the 29th asteroid to be discovered in the second half of June.

This just in! Bill Gray, creator of the charting program Guide, has created a complete list of fresh orbital elements (used to predict 2011 MD’s path) at ~ 2 1/2 hour intervals. If that isn’t current, I don’t know what is. Click HERE and scroll down to find the time (given in decimal date Universal time, ie. June 26.5 = 7 a.m. CDT Sunday) that best fits the time you plan to view the asteroid. Remember, most observers in the western hemisphere will need at least an 8-inch telescope and a map generated using the elements above to see this thing.

2 Responses

  1. The orbit for 2011 MD has been updated several days ago and since then it is known that closest approach will not happen at 13:30 but 17:00 UTC; with that the area underneath shifts by some 50 degrees. Check the orbital elements before posting on a freshly discovered solar system body – they always change during the early days.

    1. astrobob

      Daniel, you are correct. Thank you for the correction. I was concentrating so much on the asteroid’s brightness and the latest positional information, I forgot to notice the change in time of closest approach. Instead of around 8:30 a.m. CDT today as I and many other sources reported, 2011 MD will be closest to Earth around noon CDT today.

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