Dark Moon Rising: the total lunar eclipse of 27 July, 2018

The Armagh Observatory and Planetarium are holding a special event to mark the lunar eclipse, coming at almost the same time as the opposition of Mars.  The event has proved so popular that tickets sold out within a couple of hours of being released, so we have written this blog entry to tell you about what will happen if you missed out on obtaining a ticket or are going to try to observe the eclipse from elsewhere.

A new ultra-compact binary star

Approximately every other star in the Milky Way galaxy is in a ‘binary’ system. These binaries are made up of two stars orbiting around a common centre of gravity. The time taken for the stars in the binary to make one revolution is called the ‘orbital period’. Binaries have a wide range of orbital period. The closest stellar system to the Sun is alpha Centauri which has two stars not unlike our Sun orbiting around one another every 80 years. A third member of the system, Proxima Centauri, which is much smaller red dwarf star, orbits around these two stars once every 10,000 years.