Don’t miss moon and Venus February 28

Tonight – February 28, 2017 – catch the slender waxing crescent moon and the dazzling planet Venus in the western sky after sunset. The moon and Venus will be the first two celestial objects to pop out at evening dusk. That’s because these two rank as the brightest and second-brightest heavenly bodies to light up the nighttime, respectively.

Then, after night truly falls and it’s dark, try spotting the planets Mars and Uranus in a single binocular field of view …

Aim your binoculars at Mars to view Uranus nearby.

Aim your binoculars at Mars to view Uranus nearby.

Dennis Chabot of POSNE Night Sky captured this image of Mars and fainter Uranus, with bright Venus lower in the sky.

Do you have a telescope? This is a super time to aim it at Venus. This world will be passing between us and the sun on March 25 and thus, for over a month now, Venus has been displaying a waning crescent phase. In other words, as it nears the (approximate) line between us and the sun, the day side of Venus is shifting more and more away from us.

A telescope reveals Venus as a rather slim crescent. Surprisingly, perhaps, it’s better to look at Venus through a telescope at dusk than at nightfall. The glare of Venus is a bit overwhelming after dark.

Here is a collection of Venus images from December 2016 to February 2017 showing how the size and phase of Venus has changed in recent weeks. On March 25, Venus will pass between the Earth and sun. Afterwards, it’ll emerge into the morning sky. Image via our friend Tom Wildoner at LeisurelyScientist.com.

Once again, the best time to view Venus with the telescope is dusk, so concentrate on the moon and Venus before nightfall. Tonight – February 28 – Venus’ disk is approximately 17% illuminated by sunshine. However, from now until March 25, Venus’ phase will wane (get thinner) while the angular diameter of its disk will increase.

We give you some idea of what’s ahead by listing the phase and angular diameter for certain dates. Remember that 1o = 60′ and that 1′ = 60″.

February 28, 2017
Venus phase: 17% illuminated
Angular diameter: 47”

March 10, 2017
Venus phase: 8% illuminated
Angular diameter: 54”

March 20, 2017
Venus phase: 2% illuminated
Angular diameter: 59”

Venus will be very close to one second (1′ = 60″) in diameter for a few weeks, centered on March 25, 2017. It’s said that some people can actually see the crescent with the naked eye (or at least binoculars) when its angular diameter is this large.

Venus will come closest to Earth for the year on March 25, 2017 as it passes (more or less) in between the Earth and sun at inferior conjunction. See the diagram below.

By the way, at his particular inferior conjunction, Venus will pass a whopping 8o north of the sun. That far-northern inferior conjunction will give folks at northerly latitudes (United States, Canada, Europe and northern Asia) a chance to see Venus in both the evening and morning sky for several days in a row, starting on or near March 20.

Earth's and Venus' orbits

The Earth and Venus orbit the sun counterclockwise as seen to the north of the solar system plane. Venus reaches its greatest eastern elongation in the evening sky about 72 days before inferior conjunction and its greatest western elongation in the morning sky about 72 days after inferior conjunction. This world exhibits its greatest illuminated extent midway between a greatest elongation and an inferior conjunction.

Bottom line: On February 28, 2017, seek out the moon and Venus at dusk, and then look for Mars and Uranus in the same binocular field at nightfall.

Bruce McClure

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