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Octans and Apus circle the south celestial pole

Star chart showing 2 dim constellations and their outlines, Octans and Apus.
Octans and Apus (the Octant and the Bird of Paradise, respectively) lie far south. In fact, Octans is home to the south celestial pole. Look for them from the Southern Hemisphere on September evenings. Chart via Chelynne Campion/ EarthSky.

Octans and Apus

Octans the Octant and Apus the Bird of Paradise circle the south celestial pole. If you want to see them, you’ll have to be in the Southern Hemisphere. In fact, the south celestial pole lies inside the constellation boundary for Octans.

Both of these constellations are south circumpolar constellations. The north has circumpolar constellations too. Constellations such as Ursa Minor, Ursa Major and Draco can be seen any night of the year from the Northern Hemisphere. Octans and Apus are two constellations that Southern Hemisphere observers can view on any clear evening.

Octans the Octant

The most important fact about Octans is that it contains the south celestial pole. In the Northern Hemisphere, Polaris marks the location of the celestial pole. But in the Southern Hemisphere, there is no bright star in this location. However, there is a galaxy that is nearly at the location of the south celestial pole. It’s just extremely dim. The galaxy has the fitting name of Polarissima Australis, and it shines at magnitude 13.5.

The brightest star in Octans is a middling magnitude 3.73: Nu Octantis. It lies 69 light-years away. The star may be home to a super-Jovian exoplanet.

White chart with black dots for stars outlining the shape of Octans.
Star chart for Octans the Octant. The location where all the lines converge marks the south celestial pole. Chart via IAU/ Sky and Telescope/ Wikimedia Commons.

Apus the Bird of Paradise

Apus the Bird of Paradise is small, ranked 67th in size out of the 88 constellations. It lies between Octans and Triangulum Australe the Southern Triangle. The stars in Apus are quite dim. The brightest member of the constellation is Alpha Apodis at magnitude 3.83. Alpha Apodis lies about 430 light-years from Earth. Slightly fainter is Gamma Apodis at magnitude 3.86 and 150 light-years distant. This star is a strong source of X-rays.

White chart with black dots for stars showing Apus .
Star chart for Apus the Bird of Paradise. Chart via IAU/ Sky and Telescope/ Wikimedia Commons.

Bottom line: Octans and Apus are two constellations that you have to be in the Southern Hemisphere to see. Octans is home to the south celestial pole.

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