Your guide to the night sky this month
Sunday 2
The clair-obscur effects known as the lunar X and V are visible early evening and reach their peak just before 19:00 BST (18:00 UT) .
Wednesday 5
This evening’s 80%-lit waxing gibbous Moon sits 5˚ to the southeast of mag. +0.6 Saturn.
Thursday 6
Your first good opportunity to spy our Moonwatch target, the 40km crater Harpalus found north of the Bay of Rainbows, occurs this evening. Your next chances will be on the mornings of 20 and 21 October.
Saturday 8
Mercury reaches greatest western elongation, 18˚ from the Sun in the morning sky.
This evening the almost full 98%-lit waxing gibbous Moon sits 2.7˚ below mag. –2.8 Jupiter.
Sunday 9
There’s a chance to see Ganymede emerge from the eclipse of Jupiter’s shadow this morning from 01:54 BST (00:54 UT). The moon’s disc takes around 10 minutes to fully come out from the Jovian shade, to the east of the planet.
Wednesday 12
As dawn approaches, the 94%-lit waning gibbous Moon can be seen approaching Uranus, lying 1.7˚ west of the planet at 05:00 BST (04:00 UT). Uranus appears 5 arcseconds from the Moon’s southern limb at 08:33 BST (07:33 UT).
Saturday 15
This morning’s 73%-lit Moon lies 3.2˚ to the north of mag. –0.9 Mars.
Sunday 16
Catch the moon Ganymede being occulted by Jupiter at 01:03 BST (00:03 UT).
Later, just after sunset, catch the outer Galilean moon Callisto close to the Giant Planet’s northern limb.
Monday 17
Mag. –0.4 Mars lies 1.2˚ north of M1, the Crab Nebula this evening. A famous supernova remnant, the Crab is considerably dimmer than the planet at mag. +8.4.
Tuesday 18
Mag. –0.9 Mercury lies 0.8˚ from the binary star Porrima (Gamma (γ) Virginis), the pairing visible in the early morning sky after 06:30 BST (05:30 UT).
Wednesday 19
With a telescope, just after sunset see Europa, its shadow and Ganymede’s shadow transit Jupiter. Ganymede itself appears off the southwest limb. Europa exits the transit at 19:40 BST (18:40 UT) and Ganymede’s shadow at 20:10 BST (19:10 UT).
Friday 21
The Orionid meteor shower is predicted to reach its peak around 19:00 BST (18:00 UT), meaning tonight and into tomorrow morning will be the best viewing window. See The Big Three.
Saturday 22
Venus will pass 1.1˚ to the north of the centre of the Sun’s disc today as it reaches superior conjunction, marking its transition from the morning into the evening sky.
Monday 24
This morning sees an excellent opportunity to spot a very thin waning crescent Moon. Look low above the east-southeast horizon from 07:00 BST (06:00 UT) for mag. –1.0 Mercury with a 2%-lit Moon 4.1˚ above it. See The Big Three.
Tuesday 25
A partial solar eclipse can be seen from the UK between 10:00 BST (09:00 UT) and 12:00 BST (11:00 UT). The eclipse is greater towards the northeast of the UK, with maximum magnitudes of 40% coverage from Shetland. See The Big Three.
Wednesday 26
It’s a Galilean moon jackpot, with transits by Ganymede at 18:15 BST (17:15 UT), Europa at 19:25 BST (18:25 UT), Io’s shadow from 20:53 BST (19:53 UT) and Ganymede’s from 21:18 BST (20:18 UT). Io is occulted at 20:03 BST (19:03 UT).
Sunday 30
UK Daylight Savings Time ends at 02:00 BST this morning, with clocks going back to 01:00 UT.
Mars reverses direction in the sky and is now showing retrograde motion against the background stars.
Family stargazing
A safe way to observe the partial solar eclipse on the morning of 25 October (See The Big Three) is to use a piece of card with a 1–2mm circular hole in it. Important: don’t look directly at the Sun. Instead, with your back to the Sun, hold the card up so sunlight can pass through the hole onto a piece of white paper. Look at the bright dot in the centre of the dark shadow on the white paper and you’ll see it takes on the shape of the partially eclipsed Sun. Place the pinhole card a metre from the projection screen and move it back and forth until you get the sharpest image. bbc.co.uk/cbeebies/shows/stargazing
NEED TO KNOW
The terms and symbols used in The Sky Guide
Universal Time (UT) and British Summer Time (BST)
Universal Time (UT) is the standard time used by astronomers around the world. British Summer Time (BST) is one hour ahead of UT
RA (Right ascension) and dec. (declination)
These coordinates are the night sky’s equivalent of longitude and latitude, describing where an object is on the celestial ‘globe’
Naked eye
Allow 20 minutes for your eyes to become dark-adapted
Photo opp
Use a CCD, planetary camera or standard DSLR
Binoculars
10×50 recommended
Small/ medium scope
Reflector/SCT under 6 inches, refractor under 4 inches
Large scope
Reflector/SCT over 6 inches, refractor over 4 inches
GETTING STARTED IN ASTRONOMY
If you’re new to astronomy, you’ll find two essential reads on our website. Visit http://bit.ly/10_easylessons for our 10-step guide to getting started and http://bit.ly/buy_scope for advice on choosing a scope