From the July 2021 issue

How to see the Venus and Mars conjunction this month

In a public display of conjunction, see Venus and Mars at their finest.
By | Published: July 9, 2021 | Last updated on May 18, 2023
This celestial lineup over the Badlands in South Dakota on Sept. 18, 2017, features, from top to bottom: Venus, the magnitude 1.3 star Regulus, the Moon, Mars, and Mercury.
Gregg Alliss
It’s a good month for planets. Not only is Pluto reaching opposition July 17 (see “How to observe Pluto” on page 46), but on the 13th, Venus and Mars will appear close to one another in the sky — separated by less than the diameter of a Full Moon. Generally speaking, such an event is called a conjunction (though that term actually refers to when two objects share the same right ascension). This meet-up of Earth’s nearest planetary neighbors officially occurs around 2 a.m. EDT. Their closest approach, however, happens some six hours later. That’s when the separation between Venus and Mars will be a mere 28.1′.

The Moon’s thin crescent will hover near the planetary pair the two previous evenings, offering beautiful views to photographers with clear western skies. On the evening of the 11th, Venus will lie 5.5° southeast of the ultra-thin crescent Moon (5 percent illuminated), which will set about 90 minutes after the Sun. The planets themselves will appear just 1° apart, a distance that is nearly cut in half the following evening. On the 12th, Venus will stand just over 7° west of the 10-percent-illuminated Moon, which sets roughly two and a quarter hours after the Sun. Though the actual moment of closest approach occurs when the pair isn’t visible from the U.S., the evenings of both the 12th and 13th offer essentially the same separation — about 33′.

As Venus and Mars approach each other on the night of July 11 (left), a crescent Moon will hover around the pair, about 4 degrees away. July 12 (center) and July 13 (right) afford views of the nearest separation of Venus and Mars, as the Moon buzzes by the two planets and passes into Leo.
Astronomy: Roen Kelly

Where to look

On July 13th, the pair will become visible about 45 minutes after sunset, local time, low in the west. The two planets will initially stand 16° above the western horizon and then sink below it 1 hour and 42 minutes after the Sun.

You’ll probably spot Venus quite a bit earlier, too. It will be its usual brilliant self, shining at magnitude –3.9. Mars, unfortunately, will be quite a bit fainter, glowing at magnitude 1.8. That means Venus will be 190 times brighter than Mars, so you’ll have to let twilight fade some for you to be able to spot the Red Planet. Both objects will lie in the constellation Leo the Lion.

When closest, the two objects will be visible through any telescope/eyepiece combination that has a field of view of 0.5° or more. Of course, you also can see them through binoculars or with your naked eyes once the Sun is far enough below the horizon.

Past and future

The last conjunction between Venus and Mars occurred Aug. 24, 2019, when the separation between them was a bit closer: 24′. For that one, however, the planets were only 3° from the Sun, and, therefore, invisible.

The most recent visible pairing happened Oct. 5, 2017. The two planets were just 21′ apart and were 23° west of the Sun in the morning sky.

The next Venus-Mars conjunction will occur Feb. 22, 2024. On that date, 38′ will separate the pair, which will lie in Capricornus in the morning sky, 26° west of the Sun. In order to see a pairing between Venus and Mars as close as the one this month, you’ll have to wait until May 11, 2034.

An easy catch

Close pairings of naked-eye planets aren’t rare, but occurrences this easy to see don’t happen all that often. And while the event on July 13 won’t feature the closest such pairing of objects, it will be easy for anyone with a clear sky to spot, mainly because Venus is involved. Even better, it takes place in the evening. Take this opportunity to be an ambassador for easy observing as you point out the two worlds to your family and friends.