Morning moon and planets direct our attention to Comet ISON’s return

The sky facing east this morning in twilight. Mercury joined the scene lined up below Mars and Jupiter but the trees blocked the view. Credit: Bob King

The moon and planets looked great this morning, and I was surprised at how easy it was to see Mars, the dimmest of the three. Not far removed from the scene, Comet ISON bided its time, waiting for its chance in the limelight.

My viewing time was an hour and a quarter before sunrise. Tomorrow and Sunday mornings the moon will move in closer to the planets, making for even more scenic alignments.

If you’d like to take a picture of your own, it’s not difficult. You’ll need a steady mount for your camera – I use a tripod but a well-placed fence post will serve – and a camera that can take a brief time exposure. The picture above was shot in moderately bright twilight with the lens set wide open at f/2.8, ISO 400 and a 3-second exposure.

Just make sure before you shoot that your lens is focused at infinity. You can do that simply by pointing at the moon or a cloud and pressing the shutter button halfway down to lock your camera focus. Then depress all the way to begin your exposure. Include something fun in the scene if you can. If you happen to live near a body of water, you can’t beat a nice reflection.

The sky tomorrow morning Saturday Aug. 3 features a fine gathering of moon and planets. Also joining the scene but still invisible because of skyglow, is Comet ISON. ISON is expected to brighten to naked eye visibility later this year. Stellarium

Perhaps the hardest part of this particular bit of astrophotography is simply getting up before sunrise. I’ve also included Comet ISON’s location on the map a short hop to the left of Mercury. Don’t expect to see it. The comet is still too faint and lost in dawn’s glow. Later this month amateur astronomers using 10-inch or larger telescopes should be able to coax it from a darker sky.

Hubble Space Telescope photo of Comet ISON on April 30. It’s a composite of several separate exposures made in two colors of light to produce a color image.  The comet appears in front of a background of stars in our own galaxy and numerous more distant galaxies. Credit: NASA / ESA

The Comet ISON Observer’s Workshop, which began yesterday and continues through today at Johns Hopkins University Applied Physics Laboratory, is being streamed live as well as archived for later viewing. If you’d like to check it out, drop by the live stream or start from the beginning with Comet ISON Part I. I think you’ll be amazed at how many different spacecraft and ground observatories – professional and amateur – will be keeping their eyes on this comet. Add them up and it comes to more surveillance of a single astronomical object by the broadest range of instruments ever.

While some of the discussion is esoteric, there are many items of interest to glean including recent evidence that both comets ISON and C/2011 L4 PANSTARRS, which appeared this spring, might belong to a new class of “dry comets” composed of mostly dust particles from the early days of the solar system with little water ice.

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