Follow the links below to learn more about the planets in March 2018:
Mercury and Venus. March is a wonderful time to see both of these worlds, especially from the northern half of Earth. In early March, they are very low in the west shortly after the sun goes down. We’ve been receiving photos of Venus after sunset since mid-February, and Venus can act as your guide to Mercury, because it’s about 12 times brighter, in early March.
Venus and Mercury are only a little more than 1 degree apart on March 2 to March 5; 1 degree is about the width of your little finger at arm’s length. From temperate latitudes in the Southern Hemisphere, unfortunately, Venus and Mercury set almost immediately after the sun in early March and are much tougher to see. Read more about how to spot Venus and Mercury after sunset in early March.
As seen from the whole Earth, the situation improves as the month passes, and both worlds get higher in the sky. They’ll remain close enough together on the sky’s dome to fit inside a typical binocular field (about 5 degrees) for the first three weeks of March, 2018. If you spot Venus, but not Mercury, aim binoculars at Venus to see both worlds.
Mid-March will be a grand time to see Venus and Mercury, especially from the Northern Hemisphere. Mercury’s greatest eastern elongation – its greatest apparent distance from the sun on our sky’s dome – comes on March 15. This is Mercury’s best evening apparition of the year for the Northern Hemisphere.
From the Southern Hemisphere, both Venus and Mercury are harder to catch. Think of it in terms of their setting times. At mid-northern latitudes, given an unobstructed western horizon, Venus and Mercury stay out for about 75 minutes after the sun (though Mercury stays out a little while after Venus sets) in mid-March. At the equator (0 degrees latitude), Mercury and Venus set about an hour after sundown. At temperate latitudes in the Southern Hemisphere, they set some 45 minutes (or less) after sunset. Click here for recommended almanacs; they can give you the setting times for Mercury and Venus in your sky.
Venus and Mercury have a second, wider conjunction on March 18. At this time, Mercury reaches its stationary point – the point on our sky’s dome when it stops moving away from the sun, and starts dropping toward it again – while Venus overtakes it in our sky.
At this same time – on March 18 – the young moon will join Venus and Mercury at evening dusk and nightfall. Don’t miss them on these evenings!
After mid-March 2018, Mercury will quickly sink downward, closer to the setting sun. Meanwhile, Venus will climb upward, away from the sunset. Venus will remain a fixture of the evening sky until October 2018. Mercury will pass between the Earth and sun, transitioning out of the evening sky and into the morning sky, on April 1, 2018.
Jupiter. It’ll be hard to miss Jupiter in March, as it’s the brightest celestial object to light up the sky, from when it rises (around midnight in early March, as seen from northerly latitudes) until dawn, when it’s high in the sky. The planet Venus always appears brighter than Jupiter, but Venus is now a fixture of the evening sky and will remain so until October 2018. By late March, Jupiter is rising earlier, bursting onto the evening scene prior to its early May opposition. Look for it ascending in the east in late evening.
This month, Jupiter shines in front of the constellation Libra the Scales. Look for Libra’s brightest stars near Jupiter, Zubenelgenubi and Zubeneschamali (both star names are pronounced with the same ring to them as Obi-Wan Kenobi, of Star Wars). If you aim binoculars at Zubenelgenubi, you’ll see it as two stars. Zubeneschamali, meanwhile, is said to appear green in color, although, astronomers say, stars can’t look green.
Jupiter (and the constellation Libra) will be well-placed for evening viewing in another month or so. Around its May 9, 2018, opposition – when Earth flies between Jupiter and the sun, gaining a lap on the planet for this year – Jupiter will be rising in the east as the sun sets in the west, out all night, from dusk until dawn.
Look for the moon near Jupiter, especially around the mornings of March 7 and 8.
Mars and Saturn. These two worlds – so nearly alike in brightness in early March 2018 – both rise in the east in the wee hours in March. Both are visible before dawn. A good time to look for both worlds is around March 7, 8, 9 and 10, when the moon is sweeping past the morning planets (see chart above).
Mars passes from Scorpius into Sagittarius on March 11, and Saturn will already be in Sagittarius when Mars gets there. Mars spends the rest of March gradually closing the gap between itself and the ringed planet. By March 31, Mars and Saturn will be only 1.5 degrees apart. Around then, at mid-northern latitudes, Mars and Saturn rise around one and one-half hours after midnight. Meanwhile, in late March as seen from temperate latitudes in the Southern Hemisphere, these two worlds will be climbing over the southeast horizon about one hour before the midnight hour.
Mars will finally catch up with Saturn in early April, to stage a close conjunction on April 2, 2018.
By late March, Mars’ brightness will have changed dramatically, too. Earth is now sweeping up behind Mars, getting ready to pass between it and the sun in July. By late March, Mars will beam some three times brighter than the nearby red star Antares in Scorpius, and twice as bright as Saturn.
Afterwards, for some months, Mars will continue to brighten. In July, it’ll be closer to Earth and brighter in our sky than it’s been since 2003.
Exactly one year after Mars’s superior conjunction on July 27, 2017, Mars will swing to opposition on July 27, 2018. Remember Mars’ historically close opposition of August 28, 2003? That year, it was closer and brighter than it had been in some 60,000 years. This July’s opposition will be the best since then.
In fact, in July 2018, Mars will become the fourth-brightest object in the sky, after the sun, moon and planet Venus.
It’s not often that Mars outshines Jupiter, normally the fourth-brightest object. But it will in 2018.
So try to catch Mars in March 2018! Then watch for it to rise earlier – and get much, much brighter – in the months ahead.
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: In March 2018, our solar system’s two innermost planets, Venus and Mercury, are near each other in the west after sunset. Meanwhile, the three bright superior planets (those orbiting outward from Earth in orbit around the sun) – Mars, Jupiter and Saturn – can be found from midnight to dawn. Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.