Stellar Vista Observatory Sky Report: Aug. 17-23

SOUTHERN UTAH — The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate and comprehend our starry night sky. Additional information is available online. Send questions and comments to [email protected].

This week and through the next two months are a great time to watch the planets since the four brightest are out at one time or another, although not all together. Here’s where they are this week.

Jupiter and Saturn appear low in the southeast as the sky grows dark, which is around 9 p.m. Jupiter is the brighter of the two, and Saturn is a few degrees to the left. Can you notice that Jupiter is whiter than Saturn and that Saturn has a softer hue? In both cases, they shine by reflected sunlight bouncing off their atmospheres, but their atmospheres have slightly different temperatures and compositions. Powerful binoculars held steady may reveal some moons of Jupiter but not the rings of Saturn; for them, you need at least a 30-power telescope.

Here’s a task: How early can you see Jupiter? It becomes obvious a half-hour after sunset, as does Saturn. Find Jupiter one night, note its position relative to distant landmarks, and then observe 10 minutes earlier each night from the same position to discover how early you can see it in a darkening sky. Jupiter and Saturn are at their highest when they’re due south at 11 p.m., one-third of the way up the sky with an altitude of 30 degrees.

At the same time, Mars rises due east, although you won’t see it until it clears local obstructions some time later. Mars is brighter than any star and it has an orange color, so you can’t miss it. Mars is presently 50 million miles from Earth, but we’re catching it as we orbit the Sun faster and Mars is growing brighter by the week. See if you can notice it brighten between now and October, when it is closest. Mars is at its highest at 5 a.m., and by then Venus has risen in the east to join it. Venus is brighter than any other planet because it’s covered with highly reflective clouds.

Jupiter and Saturn are in the eastern part of Sagittarius, Mars is in Pisces and Venus is in Gemini, amidst the winter constellations with mighty Orion to the right. The constellations that now surround Venus – Gemini, Orion, etc. – are in the morning sky in August but in the evening sky in the winter, although Venus will be elsewhere then.

The Moon is new on Tuesday and at first quarter phase on Aug. 25.

Written by JOHN MOSLEY. 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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