SJAA Ephemeris May 2005 | SJAA Home | Contents | Previous | Next

Starry, Starry Night


Paul Kohlmiller

Location of Porrima, 3C273 and M87.


Consider poor porrima. This star's name is actually Latin based as opposed to most star names which are Arabic. Porrima is somewhat prominent these days because it appears to be leading Jupiter across the sky. By early May they are side-by-side. Porrima (Gamma Virginis) is a double star though it may be difficult to resolve them because they are getting close together from our viewpoint. The two stars rotate around each other at a distance of 40 AU, the same distance as between the Sun and Pluto. I could not resolve the double stars even after raising the magnification to 500x. The pair of nearly equal stars, each about 50% larger than the Sun, have their closest approach in 2007. Porrima is just 31 light years away. It's apparent magnitude is 3.65.

As can be seen in the chart, quasar 3C273 is close to Porrima. This quasar has a magnitude of 12.9 and is quite possibly the most distant object you can find in your telescope. It is nearly 2 billion light years away. We think we spotted it the night of April 9. It looked like a dim star and required averted vision unless you were dark-adapted. The designation 3C273 comes from being object 273 in the Third Cambridge Catalogue.

If 3C273 is a bit of a stretch, you are only 10 degrees away from M87. This giant elliptical galaxy is more than 60 million light years away. It owes at least some part of its brightness to the fact that it is surrounded by 100,000 globular clusters.

So Porrima is a great location to start viewing. You can see a double star, Jupiter, a quasar and you're close to the Virgo cluster of galaxies. And it is ideally located in May.



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