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Sunday, May 1, 2005

Seeing Ceres

Most people, even those who've dreamt of or even hoped for a life of liberty and adventure in the asteroid belt, have never actually seen an asteroid with their own eyes. If you, as I, wish to remedy this observational lacuna, the first week of May this year will provide an excellent opportunity to spot the first-discovered and largest asteroid.

Asteroid 1 Ceres is at opposition on the 8th of May and hence is visible all night. But more importantly, between the 1st and 7th of May it passes close to the bright (magnitude 2.6) star Beta Libræ (Zubeneshamali), the top of the almost perfect right triangle formed by Alpha, Beta, and Gamma Libræ in the southeastern sky as seen from temperate latitudes in the northern hemisphere around 23:00 local summer time. Ceres will be about magnitude 7.0 this week, which is right on the edge of naked eye visibility under perfectly dark and transparent skies (which, sadly, few of us enjoy), but it's an easy object with even the most modest of binoculars, which will show Ceres and Beta Libræ in the same field. Ceres will be above (toward the zenith) and to the left of Beta Libræ on May 1, moving off to the right after May 4. The following link will show Ceres in the southeastern sky from a viewpoint around the middle of the U.S. at 05:00 UTC on May 3. You can adjust the viewpoint, date, and time as you like in the boxes below the image, or click in the image to show a telescope/binocular view into which you can zoom. The grey disc with the red "A" is the asteroid Ceres--pretty spiffy graphics, don't you think?

Ceres in the southeastern sky
The orbital position calculations and image generation are done by the Fourmilab Your Sky server. If you wish to generate a custom image, remember that the date and time are specified in Universal time, and you need to take into account not only the time zone difference but the fact that Universal time does not include the summer time offset.

The following link will show where Ceres is with respect to the planets of the inner Solar System at the time it is clicked:

Ceres: Orrery View
generated by Solar System Live.

If you have more than one pair of binoculars, you can invite the neighbours to spot their first asteroid along with you--a laser pointer is great for indicating where to look in the sky. Then you can say that you've spotted Ceres in parallel!

Posted at May 1, 2005 17:57