Almost Missing Eros

I guess I’ve been too busy with family and Church things to pay much attention to the skies lately. Universe Today startled me this morning with a post on the (relatively) close approach of the asteroid Eros. Tomorrow: sixteen million miles.

If that name tickles your memory, it might be because of love. It might also be that a decade ago the intrepid space probe NEAR-Shoemaker orbited Eros, then completed its mission with a soft landing in the dust.

Sky & Telescope has a helpful chart. After spending much of January in Leo, Eros now appears in the constellation of Sextans (the sextant–accurate translation, there). Soon enough, it will drift to Hydra before withdrawing from easy view.

The fun thing about Eros will be less spotting it–you won’t be able to pick it out against background stars. At twenty-one miles across at a range of several million miles, this object appears as a point of light. The more enjoyable observing will come from tracking the asteroid’s progress on successive nights.

Magnitude 8, which it should be for a few more days, is within the means of a good pair of binoculars. Unfortunately, both my telescopes are in disrepair. I was trying to rebuild a tripod on one of them months ago. It sits gathering dust in my workroom. The other is not as powerful, but needs a good cleaning. I do have a good pair of binocs, so I’m hoping for clear skies a few nights this week.

The casual skywatcher needs to know where to look. Leo is easy enough to locate. Find the Big Dipper (Ursa Major) and the north star, Polaris, from the pointers. Leo is south of the Dipper, and is identified by the backwards question mark of the lion’s head. Eros has passed in front of the lion’s flank, and it has moved somewhat south over the past week or two. From my reading of the chart, Mars, Regulus (the brightest star in Leo) and Eros form a roughly equilateral triangle about the size of a hand at arm’s length.

If there are any homeschoolers in the reading audience, tracking Eros would be a good project for a high school astronomy student. For a casual astronomer of any age (and without a telescope), starting with Venus (now bright in the southwest after sunset) is a good task. Even in a city, an observer can stand in the same spot at the same time each evening, and watch Venus move against your neighborhood’s houses and trees as it orbits the sun.

It’s the same principle for Eros. This asteroid orbits the sun at a tilt compared to the Earth and the other planets. Eros crosses that plane from the north to the south, unlike the sun, moon, and other planets, which are seen to move along an east-west line.

So, good luck with your observing. Let me know how it turns out.