Chris Schur of Payson, Arizona got up at 4 a.m. Monday to capture a special moment. His photo of Comet ISON in a triple conjunction with the star Regulus and planet Mars is stunning – one of the coolest ISON photos I’ve seen yet.
Let’s take a closer look at what’s going on in the image. Mars is in conjunction with Regulus and also with the comet, the comet’s in conjunction with Mars and Regulus and if you look closely, you’ll notice a little blurry spot immediately to the left of Regulus. That’s the dwarf galaxy Leo I located some 820,000 light years from Earth. We’ll throw that in too and call it a quadruple conjunction. Like a good stew, the alignment contains a diverse assortment of deep space ingredients: comet, planet, star and galaxy.
Chris made the photo shortly before dawn on Oct. 14 using a 3.1-inch (80mm) refracting telescope and Canon XTi set at ISO 800. His exposure time was 10 minutes on a guided mount. The striking color differences between each object are very apparent. ISON glows green from fluorescing cyanogen and diatomic carbon gases; Mars orange from iron oxide in its soil and Regulus, a star 150 times brighter than the sun and a good deal hotter, shines pale blue-white.
Mars and Regulus are now just a day past conjunction and still only about a degree apart. I’ve included a map to help you find them at the start of dawn. See if you can tell their colors apart with the naked eye.
A heads-up for amateurs with telescopes. Tomorrow morning is the last dark, moon-free time to observe Comet ISON from mid-northern latitudes for the next couple weeks. The comet is now about mag. 10-10.5 and should be visible in 6-inch and larger scopes under good conditions.