Antlia the Air Pump on April evenings

Antlia: Star chart with two stars connected by a line, faint outline of an old-fashioned air pump.
Antlia the Air Pump is a faint constellation that lies between Hydra the Water Snake with its bright star Alphard and the more southerly constellation of Vela the Sails.

Antlia the Air Pump is a constellation in the Southern Hemisphere that people in the Northern Hemisphere can see if they live at more southerly latitudes. April is a good month to view Antlia, regardless of the hemisphere you’re in. In mid-evening in the Southern Hemisphere, Antlia will pass through the zenith, or the point that’s straight overhead. For those at southerly locations in the Northern Hemisphere, look for Antlia to pass above your southern horizon in mid-evening.

The constellation of Antlia the Air Pump

To find Antlia from the Northern Hemisphere, look below the belly of Hydra, the long and rambling Water Snake. It’s below the star Alphard in Hydra and east of bright Sirius in Canis Major. From the Southern Hemisphere, you can look between Hydra and the flowing form of the Milky Way.

Antlia’s stars are so dim that the constellation didn’t exist until the 18th century. Nicolas Louis de Lacaille, a French astronomer who visited the Cape of Good Hope in the mid-1700s, created 14 constellations out of regions of dark sky. Before then, these were simply parts of older constellations. Lacaille named these new constellations after new or important scientific instruments of his time. Antlia, for example, he named after the air pump, which had been invented in the 1600s and improved in the 1700s.

The stars of the Air Pump

The brightest star in Antlia is Alpha Antliae, which shines at magnitude 4.2. It lies about 320 light-years away.

Astronomers have found a couple of stars in Antlia to have exoplanets, but these stars (and their planets) are too faint to be seen with the unaided eye.

White star chart with black dots tracing out Antlia the Air Pump.
Antlia the Air Pump contains only dim stars. You can best see this constellation from a dark location in the Southern Hemisphere. Image via IAU/ Sky and Telescope/ Wikimedia Commons.

Deep-sky objects in Antlia

While a large swath of galaxies crosses Antlia, these distant island universes are so far away and dim that the majority of amateur astronomers would have trouble locating them. If you’re a telescope owner with lots of experience, you might be able to spot the galaxy NGC 2997. This spiral galaxy is magnitude 10.1 and appears near the border with Pyxis the Compass. William Herschel discovered NGC 2997 in 1793. It lies approximately 40 million light-years away.

Blue and pink clusters in spiral arms with yellowish center.
The spiral galaxy NGC 2997 in Antlia. Image via Adam Block/ ChileScope/ Wikimedia Commons.

Bottom line: Antlia the Air Pump is a constellation that lies in southern skies. It contains dim stars and galaxies, including NGC 2997.

April 28, 2022

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Kelly Kizer Whitt

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