Jupiter and Saturn come out first thing at nightfall in October 2020, and will continue to do so until the year’s end. They are near one another on the sky’s dome, with Saturn following Jupiter westward across the sky from dusk/nightfall until late night.
At mid-northern latitudes, Jupiter and Saturn set at late evening; and from the Southern Hemisphere, they stay out till midnight or later.
Earth – in its yearly orbit – swung between these outer worlds and the sun in July 2020. Thus we were closest to Jupiter and Saturn for the year in July. Jupiter and Saturn, in turn, shone at their brightest best and were out all night long.
All the same, these two worlds remain bright and beautiful throughout October, plus they appear highest up for the night at nightfall.
If you have a telescope, it’s best to use it when Jupiter and Saturn are highest up for the night at nightfall and early evening. These two worlds will be sinking westward as nighttime deepens, so catch them at early-to-mid evening. Typically, the view of Jupiter’s four major moons and Saturn’s glorious rings through the telescope is sharper when these worlds are higher up than lower down. The thickness of the Earth’s atmosphere near the horizon tends to blur the view of Jupiter’s moons and Saturn’s rings.
Look first for brilliant Jupiter; Saturn is the bright object immediately to Jupiter’s east. Although Saturn is easily as bright as a 1st-magnitude star – as bright as the brightest stars in our sky – the ringed planet can’t compete with the the king planet Jupiter, which outshines Saturn by some 13 times. After all, Jupiter almost always ranks as the fourth brightest celestial object, after the sun, the moon and the planet Venus, respectively (although Mars will temporarily reign as the fourth-brightest celestial body – and Jupiter as the fifth-brightest – in October 2020).
For the first time since the year 2000, Jupiter and Saturn will exhibit their great conjunction in December 2020, for the closest coupling of Jupiter-Saturn conjunctions on the sky’s dome since the year 1623. Astronomers use the word conjunction to describe meetings of planets and other objects on our sky’s dome. They use the term great conjunction to describe a meeting of the solar system’s two biggest planets, Jupiter and Saturn. The last great Jupiter-Saturn conjunction was May 28, 2000. The next one will be December 21, 2020. But October 2020 presents a fine time to start watching these worlds.
Watch for the moon in the neighborhood of Jupiter and Saturn for several days, centered on or near October 22.
Mars rises over your eastern horizon by early evening in early October, and coming up earlier daily, heading for its own opposition on October 13, 2020. This month, in October 2020, Mars actually supplants Jupiter as the sky’s fourth-brightest celestial body, after the sun, moon, and the planet Venus. You won’t want to miss this fiery red object lighting up the nighttime sky from dusk till dawn!
In October 2020, Mars exhibits its brightest performance until September 2035. Earth is now rushing along in its smaller, faster orbit, gaining on Mars, the fourth planet outward from the sun. Throughout the first half of October, watch for Mars to brighten as Earth closes in on Mars, passing between it and the sun on October 13, 2020.
Around the world, Mars rises roughly an hour after sunset in early October, around sunset in mid-October, and is up before sunset by the month’s end.
View at EarthSky Community Photos. | From Paul Armstrong, who took this photo of Mars, Saturn and Jupiter on the morning of April 15, 2020, from Exmoor, U.K. Jupiter is at the upper right, Mars at center left, with Saturn between them. In May 2020, Jupiter and Saturn were closer together, whereas Mars was farther away from Jupiter and Saturn. Thanks, Paul!
Venus – the brightest planet – reached its greatest elongation from the sun in the morning sky on August 12 or 13 (depending upon your time zone). But dazzling Venus will remain bright and beautiful as a morning “star” for the rest of this year.
At mid-northern latitudes, Venus rises about 3 1/2 hours before the sun in early October, tapering down to about 3 hours by the month’s end.
At and near the equator, Venus rises 2 1/2 hours before the sun in early October, decreasing to 2 hours at the month’s end.
At temperate latitudes in the Southern Hemisphere, Venus rises about 1 2/3 hours before the sun in early October, tapering to 1 1/2 hours by the month’s end.
Throughout October, Venus in its faster orbit around the sun will be going farther and farther away from Earth. As viewed through the telescope, Venus’ waxing gibbous phase will widen, yet its overall disk size will shrink. Venus’ disk is 72% illuminated in early October, and 81% illuminated by the month’s end; Venus’ angular diameter, on the other hand, will shrink to about 85% of its initial size by late October.
Watch for the waning crescent moon to shine with Venus in the morning sky for several days, centered around October 13 or 14.
Mercury showcases a fine evening apparition during the first week of October 2020 in the Southern Hemisphere. Mercury reaches its greatest evening elongation from the sun on October 1, 2020, and remains a whopping 25 degrees east of the sun until October 7, 2020. Even so, Mercury sits too close to the afterglow of sunset to be visible at northerly latitudes. Mercury shifts out of the evening sky and into the morning sky during the second half of October, and might become visible in the morning sky from northerly latitudes by late October.
What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.
Bottom line: October 2020 presents 4 of the 5 bright solar system planets in the evening sky (Mercury only nominally so at northerly latitudes). Catch Jupiter and Saturn at nightfall, Mars at early evening, and Venus in the predawn/dawn sky.