Close But No Cigar

My older daughter walked in the front door just before 9:30 last night and called out a greeting. Good thing she did. I’d fallen asleep on the couch while on watch for the 9:28 p.m. Iridium satellite flare.

"Hi Dad, I’m home," she said. Roused, I looked at my watch. Yikes, only 30 seconds to go. I hurried down the steps, grabbed my daughter and we looked up in the east. The flare was just beginning, and swelled to a brilliant glow in the next few seconds. We were both wowed by what we saw, and now my daughter thinks Iridiums are pretty cool.

I hope you had the chance to see it too. If not, there are more flares on tap. Just check the table from yesterday’s blog.


Arecibo telescope radar echo image of the asteroid Apophis — L. Benner/JPL

Maybe you’ve heard about the potential doomsday asteroid 99942 Apophis. This hunk of rock about 1,100 feet across will make a close brush with our planet on Friday April 13, 2029. If its orbit is altered by passing through a narrow region in space near the Earth at that time, there’s a remote chance it would actually collide with our planet on its return visit on April 13, 2036, Easter Sunday. NASA predicts the odds of this happening at 1 in 45,000. Don’t tell grandma to bake that pie just yet.

Apophis has been in the news this week because 13-year-old Nico Marquardt from Germany supposedly determined that NASA was wrong about the odds of the collision. Marquardt predicted that in 2029, Apophis could stike one of the many telecommunications satellites that orbit in a dense belt  about 22,000 miles above Earth’s equator. That would alter its orbit so that on the 2036 return, the odds of a strike would increase to 1 in 450, one hundred times greater than NASA’s prediction.

It’s true that Apophos will pass only 18,300 miles from Earth’s surface in 2029, well within the distance of the satellite belt. What Marquardt didn’t take into account was that the close approach would happen at an angle to the equator and out of harm’s way of any telecommunications satellites.

 "We have not corresponded with this young man and this story is absurd, a hoax or both," said Don Yeomans, an asteroid expert at NASA. Nor will Apophis hit the moon. However if you’re in the right place on Friday the 13th, 18 years from you —  Europe for instance — you’ll be able to look and watch a fast moving "star" cross the sky. It’ll be close, yes, but no cigar.