International Year of Astronomy - South Africa

Astronomy Questions


Have a question about astronomy? 

Here are links to SAAO's viewing the sky and frequently asked questions webpages.  Also, you might be interested in astronomy books. 

Some additional questions and answers are provided below.

 

On one of the episodes of the British quiz series Quite Interesting they said that the Earth actually has two moons - the one we know and one called "Cruithne". Is that in fact a second moon?

Cruithne is a small asteroid moving on an orbit which is similar to that of our Earth. However, it circles the Sun rather than the Earth and hence isn't regarded as a moon. In-depth information about Cruithne (including an explanation of what its name means) can be found at http://www.astro.uwo.ca/%7Ewiegert/3753/3753.htm. There are other asteroids which move close to Earth, spiralling like a corkscrew around the Earth's orbit, as illustrated below for the asteroid AA29.

  

You may find this image as well as an MPEG animation of AA29's orbit on http://science.nasa.gov/headlines/y2006/09jun_moonlets.htm.