Page 21 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

NEED TO KNOW

Right ascension

Constellation border

Ecliptic

Milky Way

Declination

STAR CHART KEY

GALAXY
overall view, you can identify stars that are variable objects. As a beginner it’s probably the seasonal
PLANETARY NEBULA
(change in brightness) or double (optically or or monthly charts that you’ll use the most, so
gravitationally together in the sky). make sure you’re happy with the style. DOUBLE STAR
Depending on your atlas there may also be If you’re technologically up to speed, a great VARIABLE STAR
additional symbols for deep-sky objects such as way of creating star charts is by using computer OPEN CLUSTER
nebulae, galactic star clusters, globular clusters, software. A large number of programs are available GLOBULAR CLUSTER
planetary nebulae and galaxies. (some of them free) that allow you to zoom in
But let’s go back to map scales. A useful atlas and out and have the added benefi t of positioning
should have charts that vary in detail. You may, for the planets and the Moon for any day you wish.
example, have general seasonal charts or monthly Computers do have their limitations, though: they
charts, close-ups of some constellations and can run out of power, they don’t like dew and they
possibly a location chart for some of the deep-sky crash. You don’t get that with a magazine!

ij k / l mop q r s t
Nu Xi Omicron Pi Rho Sigma Tau Upsilon Phi Chi Psi Omega

Other astronomers have also assigning alpha to the brightest, differently – they are the Latin
had their turn at ordering the then beta, gamma, all the way to for ‘belonging to Ursa Major’.
stars, which up until the early omega. Using Ursa Major as an All constellations have a Latin
17th century were mainly known example, the Arabic star Dubhe is possessive, such as Geminorum
by Arabic names. Johann Bayer, not the brightest in the constellation for ‘belonging to Gemini’.
in homage to the earlier Greek but was labelled by Bayer as Each of the constellations
astronomers, labelled the brightest alpha, and so is formally called also has its own three-letter
stars of a constellation with Greek Alpha Ursae Majoris. You’ll notice abbreviation: Ursa Major’s is UMa
letters – usually, but not always, that the last two words are spelt so Dubhe, again, would be _ UMa.
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