Page 14 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

DUBHE

JARGON BUSTER
• ASTERISM A pattern of
bright stars that can be easily MERAK
TILL CREDNER/ALLTHESKY.COM, ADE ASHFORD X4, JERRY LODRIGUSS/SCIENCE PHOTO LIBRARY
found again and again. ALCOR MEGREZ
Famous asterisms include the MIZAR
Plough, the Summer Triangle ALIOTH
and Orion’s Belt.
• DOUBLE STAR Two stars
that appear very close PHECDA
together. They may actually
be orbiting each other, in ALKAID
which case they are known
as a binary double, or they
can simply appear to be close
because of our viewpoint in
space, in which case they are
known as an optical double.
• STAR COLOURS Stars
can be different colours
depending on the amount of
gas they are made of and
how far through their lives
they are. Get to know the stars that make up the Plough: Alkaid, the Alcor-Mizar double, Alioth, Megrez, Dubhe,
Phecda and Merak. In case you’re wondering, these stars all owe their names to medieval Arabic astronomers

SIGNPOSTS

IN THE STARS

USE THE PLOUGH AND OTHER STARRY SHAPES TO
FIND YOUR WAY AROUND THE NIGHT SKY

FINDING

#!33)/0%)!
YOUR WAY $UBHE -ERAK

FROM THE h7v 0OLARIS $UBHE #ASTOR '%-).)
0OLLUX
PLOUGH 523!-)./2 h0LOUGHv 523!-!*/2 h0LOUGHv -ERAK 3ATURN

The Plough doesn’t -EGREZ 523!-!*/2 #!.#%2
just help you to fi nd
Polaris. Here are
four more stars, and
their constellations, that ❯ CASSIOPEIA ❯ CASTOR AND POLLUX,
You’ve already seen how to locate Polaris. Now THE TWINS OF GEMINI
the Plough will point continue this imaginary line onwards for the same To get to Castor and nearby Pollux, the main stars of
you towards distance that you’ve already come from the Plough, Gemini, the Twins, start from the Plough star Megrez.
take a slight bend to the right, and you arrive at Head for Merak, diagonally opposite it, and keep
the constellation of Cassiopeia, the Queen, which going. Almost halfway to your target you’ll pass the
appears in the form of a W-shaped group of stars. two stars that form the front paws of Ursa Major.
14 skyatnightmagazine.com 2012