Southern Hemisphere

octans is the constellation at the south celestial pole, devised in the 18 th century by the French astronomer Nicolas Louis de Lacaille. It represents a navigational instrument called an octant, a predecessor of the sextant. The octant was invented in 1731 by the English instrument-maker John Hadley. this area of sky is quite barren, with no bright star to mark the position of the pole as Polaris does in the northern hemisphere Because of the effect of precession (see p.133 the positions of the celestial poles are constantly changing, and the south celestial pole is moving in the direction of Chamaeleon.

lambda (X) oCTANTIs 5 A double star divisible with a small telescope. The components are of 5th and 7th magnitudes.

Sigma (a) octantis 2 1 The nearest star to the south celestial pole detectable with the naked eye. A yellow-white giant, it lies 270 light-years away. However, it is only of magnitude 5.4 and thus far from prominent. Currently it is just over one degree from the celestial pole, but this distance is increasing due to precession.

southern pole star trails

Stars spin around the south celestial pole in this long-exposure photograph taken from Australia. Unlike in the north, there is no bright star near the southern pole.

southern pole star trails

Stars spin around the south celestial pole in this long-exposure photograph taken from Australia. Unlike in the north, there is no bright star near the southern pole.

Was this article helpful?

0 0
Telescopes Mastery

Telescopes Mastery

Through this ebook, you are going to learn what you will need to know all about the telescopes that can provide a fun and rewarding hobby for you and your family!

Get My Free Ebook


Post a comment