Venus Remains In Hiding, But You Can’t Miss The Waning Moon

In this photo taken earlier today above Earth’s atmosphere by SOHO, a disk blocks the sun, letting us see not just Venus but Mars, Leo’s brightest star Regulus and a host of fainter stars. The sun’s position is shown by the white circle, and rays sticking out either side are part of the sun’s outer atmosphere called the corona. The bright line through Venus is an electronic effect due to overexposure. NASA / ESA

Venus has been hiding for weeks near the sun in the morning sky. On Aug. 14 it was in conjunction with the sun. Since that date the solar system’s most reflective planet has been inching into the evening sky. Right now it’s just a few degrees from the sun and hopelessly lost from view in its glare. Only the orbiting SOHO (Solar Heliospheric Observatory) spacecraft can spot it. It does this by using an opaque mask called an occulting disk to block out our offending star.

As Venus cycles around the sun very 225 days, it passes between the Earth and sun in inferior conjunction and on the opposite side of the sun in superior conjunction. During this time, the changing angle the planet makes with the sun causes it show phases just like the moon. Venus passed superior conjunction — when it was lined up with Earth on the opposite side of the sun — on Aug. 14. Bob King

With the sun masked from view it’s easy to see Venus and a whole lot more, including the star Regulus and another planet, Mars. Mars is also too close to the sun to see from the ground. As Venus orbits the sun, moving slowly to the east (left) each day, it will move further and further away from the solar glare until it’s visible in the western sky shortly after sunset. The key word here is slowly. The track the planet takes in the evening sky will be a low one, with Venus hovering near the southwestern horizon in evening twilight throughout late summer and fall.

We’ll first see it in the first week of October low in the southwestern sky. It will climb a little higher each week and finally become super-obvious in mid-December. Venus meets up in conjunction with Jupiter on Nov. 24 and with Saturn on Dec. 11. Just because we can’t see Venus for a time doesn’t mean you can’t enjoy its travels. In the next few weeks, with Venus so near the sun, go to this SOHO link and click the LASCO C3 photo to see daily images of its progress.

A Venus-Mars conjunction happens on Aug. 24. See it online. Click the link and download a copy of Stellarium for your PC or Mac. Stellarium 

Because the planets all follow the same basic path in the sky called the ecliptic I knew it wouldn’t be long before Venus would overtake Mars. So I checked Stellarium and sure enough they’ll be in close conjunction about a quarter-degree apart around sunrise on Saturday, Aug. 24. Don’t try to see it with your eyes — it’s completely invisible in daylight. Go over to the link above and watch it online.

The waning gibbous moon stood high above the trees this morning well after sunrise. Bob King

Something you can see is the waning gibbous moon in the post-sunrise morning sky. I spotted it high in the southwest around 9 a.m. as crisp and bright as could be. Recall that the sun and moon and planets follow essentially the same path in the sky. Right now, the late-rising moon (waning gibbous through waning crescent phases) is traversing the same section of “highway” the sun cruises from late spring through early summer. That part of the sun’s path crests high above the horizon, making for long hours of sunshine. Similarly, the waning moon from late summer into early fall rides high in the sky. It’s up for hours and sets late just like the summer sun.

You should be able to track the moon’s eastward motion of about one fist a day from now until about Aug. 25 as you watch the moon’s phase wane from gibbous to crescent.