21-22 February 2015 -- Evening Sky
By Martin Lewicki, Adelaide Planetarium, South Australia.
Lately you probably have noticed brilliant Venus gracing our western sky after dusk as the Evening Star. Less noticeable is much fainter and more distant Mars, just a few degrees east of Venus. You are more likely to spot Mars in binoculars in the light of twilight.
If you are in northern latitudes look a few degrees above Venus; and from southern latitudes look the same distance to the upper right. Each night as the two planets continue in their motion around the Sun they will appear to edge closer together.
On 21st February (NH) and 22nd (SH) they will be in conjunction as they pass 0.4 degrees apart which is a bit less than the width of the full Moon. Venus will be 212 million kilometers away from us and Mars is nearly two-thirds as far behind it at 331 million kilometers. To complete the picture a thin crescent Moon will appear be near the pair making for some nice photo opportunities.
Venus and Mars also have an orbital resonance with Earth so that a particular conjunction on a particular date reoccurs on nearly the same date in the same part of the sky every 32 years. A check of your favorite planetarium software will confirm that they appeared together in the same part of the constellation Pisces in almost the same star field on 19 February 1983.
Martin Lewicki is an Astronomy educator at the Adelaide Planetarium in South Australia. A member of the Astronomical Society of South Australia he heads their light pollution section and especially enjoys following the meanderings of the planets and looking out for those occasional enchanting groupings in the night sky.
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