Public Meeting 11th September 2018

~  Our next meeting is scheduled for 11th September 2018


Checking Out the Neighbours:

Searching for planets in the Alpha Centauri system

 Centaurus & Crux constellations

The Centaurus constellation includes Alpha Centauri and Beta Centauri, both easily seen near the Southern Cross (Crux) constellation without telescopes.

(Image Credit: Starry Night Education)

The Alpha Centauri triple stellar group is in the direction of the southern constellation Centaurus (The Centaur). Two bright stars, Alpha Centauri A and Alpha Centauri B, form a binary system orbiting each other. The distance between the two is about the distance from our sun to the planet Uranus. The third star, Proxima Centauri, is a dim red dwarf and possibly may be orbiting the other two; once every several million years that is.

Alpha Centauri distance

At just over 4 light-years away these three stars are the closest to our star, the Sun. Proxima Centauri is currently positioned a little closer to Earth than the other two, and so holds the distinction of being the closest star to us.

The closest star system to the Earth is the famous Alpha Centauri group. Located in the constellation of Centaurus (The Centaur), at a distance of 4.3 light-years, this system is made up of the binary formed by the stars Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf Alpha Centauri C, also known as Proxima Centauri. The NASA/ESA Hubble Space Telescope has given us this stunning view of the bright Alpha Centauri A (on the left) and Alpha Centauri B (on the right), flashing like huge cosmic headlamps in the dark. The image was captured by the Wide Field and Planetary Camera 2 (WFPC2). WFPC2 was Hubble’s most used instrument for the first 13 years of the space telescope’s life, being replaced in 2009 by WFC3 during Servicing Mission 4. This portrait of Alpha Centauri was produced by observations carried out at optical and near-infrared wavelengths. Compared to the Sun, Alpha Centauri A is of the same stellar type G2, and slightly bigger, while Alpha Centauri B, a K1-type star, is slightly smaller. They orbit a common centre of gravity once every 80 years, with a minimum distance of about 11 times the distance between the Earth and the Sun. Because these two stars are, together with their sibling Proxima Centauri, the closest to Earth, they are among the best studied by astronomers. And they are also among the prime targets in the hunt for habitable exoplanets. Using the HARPS instrument astronomers already discovered a planet orbiting Alpha Centauri B. In August 2016 astronomers announced the discovery of an Earth-like planet in the habitable zone orbiting the star Proxima Centauri. Links: Pale Red Dot Campaign ESO press release on Proxima Centauri

Hubble’s best image of Alpha Centauri A and B

(Image credit: ESA/NASA)

As our nearest stars, the Alpha Centauri system is the obvious target for the search for exoplanets. Our program looks at this interesting topic.


Make a note

Checking Out the Neighbours:

Searching for planets in the Centauri system

at our Fergusson Park Observatory, Tilby Drive, Matua, Tauranga

on Tuesday 11th September at 7.30pm.

This artistÕs impression shows the planet orbiting the star Alpha Centauri B, a member of the triple star system that is the closest to Earth. Alpha Centauri B is the most brilliant object in the sky and the other dazzling object is Alpha Centauri A. Our own Sun is visible to the upper right. The tiny signal of the planet was found with the HARPS spectrograph on the 3.6-metre telescope at ESOÕs La Silla Observatory in Chile.


Our telescopes will be operating – dependent on lack of cloud cover.




Affliated With:


With funding support from:


Slooh Space Camera


NASA astronomy picture of the day