Not One But Two Crescents Shine On Evening Skywatchers

Two crescents over Duluth, Minn. U.S. at dusk yesterday Jan. 2. One you can see just by looking up;  the other you’ll need binoculars for. Credit: Bob King

Last night the crescent moon joined a teeny tiny crescent Venus at dusk. Tonight you can watch for them again. While no optical aid is needed to enjoy a lunar crescent, Venus needs a helping hand. If you have binoculars that magnify at least 7x, point them at the planet and you’ll see a miniature replica of tonight’s crescent moon.

Venus through a 300mm telephoto lens and 1.4x teleconverter last night. This is how the planet will look through a pair of binoculars. Credit: Bob King

It’s a sight not to miss. Why? Venus is rapidly approaching the sun from our perspective and will soon pass between Earth and the sun. As the angle it makes to the sun narrows, we see less and less of the planet illuminated by sunlight until little is left but a skinny crescent. It’s a big crescent too because Venus is the closest it’s been to Earth since June 2012.

Diagram shows Venus’ orbit around the sun. Right now it’s ALMOST lined up between sun and Earth and shows as a very thin crescent. On Jan. 11 Venus will be at inferior conjunction – directly between sun and Earth – and then move west of the sun and appear in the morning sky. Illustration: Bob King

Comet next Saturday Jan.11, the planet undergoes inferior conjunction when it slides between sun and Earth. You won’t see it that day or for a week or two after as the planet will be lost in the sun’s glare. By about the 20th, Venus will “switch side”, rising in the east before sunrise. That’s why now is the time to catch the waning Venusian crescent before it’s too late.

Crescent Earth on Jan. 1, 2014 photographed by the GOES East satellite. Credit: NASA

While we’re on the topic of sickle-shaped celestial objects, even Earth can look like a crescent moon from the right perspective. The photo was taken by the GOES-13 East weather satellite on New Year’s Day from geostationary orbit from a distance of about 22,200 miles (36,000 km).

14 Responses

  1. Guy S

    I got a similar photo of the crescent pair last evening but with a more rural foreground.

    Any advice on the purchase of a teleconverter so I can increase the reach of my stellar photography?

    1. astrobob

      Hi Guy,
      Crescents are irresistible, aren’t they? Teleconverters are nice but I rarely use them for astrophotography because I lose a stop of light. Usually when I want to get in close for moon photos I’d normally use a telescope with an adapter for the camera. If you get a teleconverter just get a high quality one because you’re adding extra glass between you and the object. What are you hoping to shoot?

  2. caralex

    Caught a glimpse of Venus just after sunset through a gap (fortuitous!) in the clouds. It seemed a good height above the horizon, so I was wondering just how quickly it’ll lose altitude in the next few days if it’s to reach conjunction in exactly a week’s time. How much ‘lower’ will it appear each evening until it disappears?

    1. astrobob

      It’s dropping toward the sun right now at the rate of about 1 degree per day. I also saw Venus just before sundown in a blue sky this afternoon in 8x binoculars. Very distinct crescent.

        1. astrobob

          The next evening apparition will be in Gemini on June 6, 2015 and much better than both the Nov. 2013 evening apparition and upcoming March 22, 2014 morning appearance. Even better – Oct. 26, 2015 morning and Jan. 12, 2017 evening apparitions when Venus will stand about as high as it can get above the horizon near sunset/sunrise.

      1. Sean

        yep, caught that crescent again myself just after sunset, and tracked Venus off and on till it “set” behind some clouds just above the horizon about 45 minutes later.

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