Bye-Bye Venus, See You On The Flip Side!

Venus over the Pacific Ocean from Maui. Bob King

Venus played the part of night light this spring and summer, shining every evening in the western sky. But in the past few weeks it’s drawn closer and closer to the sun until it’s now lost in the solar glare. Farewell friendly planet.

We’ve talked about conjunctions before in the context of the moon being “in conjunction” with a bright planet. You probably saw at least one these pairings over the summer when Mars, Saturn, Jupiter and Venus stood like pinball targets across the southern sky.

As Venus plies its 225 day orbit, it passes between the Earth and sun (inferior conjunction) and around the opposite side of the sun in superior conjunction. Because of its ever-changing angle to the sun Venus shows phases just like the moon. At inferior conjunction, it’s a thin crescent and closest to the Earth. Bob King

Planets can also be in conjunction with the sun, too. And as you’d guess, those conjunctions aren’t visible because they only happen in daylight. Venus will be in conjunction with the sun tomorrow (Oct. 26), when it slides just 6° to its south at closest approach. Inner planets experience two types of solar conjunctions: inferior and superior. An inferior conjunction occurs when Venus or Mercury passes between the Earth and the sun. At this time, Earth and either planet are at their closest. When Venus or Mercury lines with the sun on the opposite side of its orbit, it’s in superior conjunction and farthest away.

Although we can’t see Venus from the ground because of the overwhelming light of the daytime sky, the orbiting NASA/ESA SOHO solar observatory doesn’t have to deal with the atmosphere and plainly shows the planet yesterday evening at 9:06 p.m. Central Time. A special mask  blocks the sun’s glare. NASA/ESA

You can see from the diagram this is an inferior conjunction of Venus, so the planet’s very close to us right now — only 25.4 million miles or 10 million miles closer than Mars’ closest approach back in July. This has a couple interesting consequences: Venus looks really big and it’s moving fast from our perspective. Good news if you can’t wait to see it again. Venus hurries from the sun into the morning sky in a little more than a week!

Venus first returns to view in the dawn sky about Nov. 3. Stellarium

Notice that as it makes the transition from evening to morning, its phase changes from a super-thin crescent open to the left (east) to a super-thin crescent open to the west. You can see why — it switches from one side of the sun to the other, again from our perspective here on Earth.

The moon will sweeten the scene and offer a helping hand in finding Venus on Nov. 6. The planet will also have risen higher by that date. Stellarium

We’ll start to see Venus reappear low in the southeastern sky shortly before sunrise on or about Nov. 2, and it will quickly climb higher and become easier to spot as the month fills out. If you need a little help, and who doesn’t when it comes to the sky, a thin moon will join equally wiry Venus on the morning of the 6th. Bring binoculars to help you find the planet. Once found, whether by eye or glass, even low power binoculars (7x and up) will show the planet’s remarkable crescent outline.

Say goodbye for now but be prepared to welcome Venus back very soon!