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Waning moon close to Mercury and Saturn at dawn December 1


Tonight for November 30, 2013

The featured sky chart above shows the southeastern sky for about one hour before sunrise on December 1, 2013, as viewed from North American mid-northern latitudes. But a similar view can be seen from around the world – only oriented differently, with the moon closer to or farther from the planets – by those who have an unobstructed horizon and possibly binoculars to spot Mercury beneath the waning crescent moon.

Meanwhile, the sky chart below shows the position of Comet ISON for about 40 minutes before sunrise on December 1. But you will not see the comet there. The comet is still too close to the sun’s glare on December 1 to be visible. If and when it does appear, it’s almost certain now it will not be a bright comet. It likely won’t be visible to the eye. That said, this is the part of the sky where Comet ISON will be:

It's a long shot but you can try your luck at catching Comet ISON in the harsh glow of morning twilight on December 1, 2013.

It’s a long shot but you can try your luck at catching Comet ISON in the harsh glow of morning twilight on December 1, 2013.

At mid-northern latitudes from Europe and Asia, the thin waning crescent moon will pair up more closely to the planet Saturn on the morning of December 1. But from anywhere worldwide, look first for the waning crescent moon, and then look for the nearby planets Saturn and Mercury. If you have binoculars, they will help, or perhaps even be necessary, to see this predawn view!

What is that glow on the darkened portion of the crescent moon? It’s called earthshine.

Saturn, though not as bright as Mercury, may be the easier planet to spot. That’s because Saturn shines higher in the sky at early dawn and doesn’t sit as deeply in the glow of morning twilight.

Mercury and Saturn both reside on the far side of the sun as seen from Earth, though at much different distances. Astronomers often like to give planetary distances in terms of the Astronomical Unit (AU): the Earth/sun distance. One Astronomical Unit = approximately 150 million kilometers or 93 million miles.

Mercury, the innermost planet of the solar system, now resides at about 0.4 au from the sun and 1.28 au from Earth. Saturn, the sixth planet outward from the sun and the most distant world that we can easily see with the unaided eye, lodges way out there at about 9.9 au from the sun and 10.8 au from Earth.

Bottom line: On the morning of December 1, 2013, as darkness gives way to dawn, let the moon guide your eye to Mercury and Saturn, the closest planet and farthest planet from the sun, respectively, as easily viewed with the unaided eye. It’s in the same part of the sky that you might have looked for Comet ISON in another day or two. But, by all reports, it’s likely we’ll get a bright comet. At most, we might expect a comet that skilled photographers and amateurs can capture using cameras, binoculars and telescopes. At worst … ISON may be gone.

Recommended sky almanacs for the moon and planets in your sky

What is earthshine?