Jul 29

Sky Report: July 31 – August 6, 2023

What happened to Venus? It was reliably there in the evening sky for months, and then it quickly disappeared.

This is easier to understand with a diagram than with words alone, so refer to the diagram which is largely self-explanatory. Venus orbits faster than the earth on an inside track, so it catches and passes us, moving from the east of the sun – when it is in the evening sky – to the west of the sun – when it is in the morning sky. Its motion in the sky appears to be fastest when its closest to us, so it moved quickly in the final days of June and first of July.

The diagram shows that Venus will reappear to the right of the sun – in the morning sky – just as quickly as it left the sun in the evening sky, so late in August it’ll pop back into view in morning twilight, and it’ll quickly gain altitude. Then it’ll be the brilliant “morning star” the rest of the year.

Note that Venus passes closest to the sun (as we see it) on August 13, but it won’t pass in front of the sun. At closest it is 8° below (south of) the sun. Our orbits have to line up just right for Venus to “transit” across the face of the sun, and that won’t happen again until 2117.

Note also that Mercury does the same thing as Venus, although being closer to the sun it goes through a similar set of motions much more quickly, and of course it stays nearer to the sun. Mercury will pass between the earth and Sun on September 5.

With Venus gone we’re left with Mars and Mercury low in the west in evening twilight. 35 minutes after sunset Mercury is only 7° high in the west and Mars, which is fainter, is 8° to the upper left of Mercury. You’ll need a flat horizon and probably binoculars.

There’s one more planet in the evening sky, Saturn. Saturn rises toward 10 p.m. The moon is near Saturn on the night of the 2nd.

Jupiter follows about 3 hours later, and it’s far brighter than any star so you can’t miss it.

The so-called “supermoon” of August 1 is the first supermoon of the month; the second is on August 30. You can read what I think about the nonsense surrounding these nonevents by going to the Sky Reports archive at https://stellarvistaobservatory.org/category/sky-reports/ and scrolling back to the week of July 3-9.

Once the moon is several days past full and the sky once again is fully dark, at least until moonrise, be sure to look for meteors. The famous Perseid Meteor Shower which peaks on the night of the 12th, has already started, although it’s ramping up to maximum slowly, but there are several other minor showers, some of which last a long time, that combine to make summer an especially rewarding time to get comfortable and watch for meteors. You’ll also see a lot of satellites. Two especially good references are: https://www.space.com/summer-meteor-showers-2023-explained and https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/.

Stellar Vista Observatory provides portable telescopes and tripod mounted binocular kits on loan for free to residents and visitors in Kane County. Enhance your enjoyment of the night sky! To learn more, request a loan, or attend one of SVO’s free public star parties for 2023, visit https://stellarvistaobservatory.org/ or drop in to the Kane County Office of Tourism.

About the Author:

John Mosley was Program Supervisor of the Griffith Observatory in Los Angeles for 27 years and is the author of “Stargazing for Beginners” and “Stargazing with Binoculars and Telescopes”. He and his wife live in St. George where he continues to stargaze from his retirement home while serving on the advisory committee for Stellar Vista Observatory.

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