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Tuesday, October 19, 2010


The Sky This Week - Thursday October 21 to Thursday October 28

The Full Moon is Saturday October 23. Mars near the head of the Scorpion. Venus low on the horizon. Venus's crescent shape is easily seen in small telescopes and good binoculars. Jupiter is easily seen in the evening sky. Comet 103P Hartley at its brightest. Variable star Mira bright.

Evening sky looking East as seen from Adelaide at 9:00 pm daylight saving time on Wednesday October 27 showing Jupiter close to Uranus. Jupiter is just past opposition, but is still excellent in telescopes and binoculars. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The Full Moon is Saturday October 23.

Jupiter rises before sunset, and can be readily seen from about 7:00 pm local time just above the eastern horizon.

Jupiter was at opposition on Tuesday September 21, when it is was its biggest and brightest as seen from Earth. However, Jupiter will still be excellent in binoculars and small telescopes for many weeks to come.

Jupiter and Uranus are close together and can be seen near each other in a pair of binoculars. Uranus is the brightest object within a binocular field north of Jupiter, and is in fact bright enough to be (just) seen with the unaided eye under dark sky conditions. A binocular spotters map is here.

Ganymede has just come out from Jupiter's disk and is about to be eclipsed, Europa is about to enter Jupiter's disk on October 27 at 23:15 ACDST (23:45 AEDST).

Jupiters' Moons are a easy to see whether you have binoculars or a telescope. Watching their eternal dance is always rewarding. The evening of Wednesday October 27 is again particularly busy, with Ganymede coming out from behind Jupiter's disk (23:15, 27 Oct ACDST) then disappearing in Jupiter's shadow (00:28, 28 Oct ACDST), Europa enters Jupiter's disk and later its shadow falls on Jupiter's disk, finally Io disappears behind Jupiter (01:10, 28 Oct ACDST).

This occurs fairly late in the evening, but still early enough to watch and head off to bed without too much loss of sleep.

There are lots of opportunities in the rest of the month to see cool Jupiter Moon events (scroll down until you hit Jupiter).

Evening sky looking North-west showing the Venus and Mars at 8:15 pm local daylight saving time on Friday October 22. Click to embiggen.

Bright white Venus is rapidly heading towards the horizon, and this week it disappears into the twilight. At the begining of the week Venus is visible above the western horizon from half an hour after Sunset, (even before) until just after the end of twilight (about an hour after sunset). By the end of the week Venus is setting just half an hour after Sunset, deep in the twilight.

Venus is in the constellation of Virgo this week. Venus is now well below Mars and draws further away as the week progresses. Venus is visible crescent in small telescopes and 10x50 or stronger binoculars, and becomes dramatically bigger and thinner over the week. Venus's close proximity to the horizon makes telescopic observation extremely difficult, and almost impossible by the 28th.

Mars is distinguishable by its reddish colouring and is the brightest object above Venus. During the week it draws closer to the head of the Scorpion.

Saturn is now lost in the twilight.

The variable star Mira is very bright.

Venus is a distinct crescent, and grows measurably bigger during the week. In my 10x50 binoculars on a tripod mounting Venus is very small but the crescent shape is easily visible. If your binoculars don’t have decent anti-glare coatings, you may have to observe in the early twilight in order to see Venus’s shape without internal reflections from the binocular lenses getting in the way.

If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums. Jupiter is well worth telescopic observation, and even in binoculars its Galilean moons are easily seen.

Comet 103P Hartley above the northern horizon at 4:30 am ACDST (3:30 non-daylight saving time) as seen from Adelaide on October 22, similar views will be seen from other places at equivalent local time.

Comet 103P Hartley 2 rises higher in the southern skies this week. The comet will be at its brightest on October 22, but will still be faint, between magnitude 5-4, and will be seen as a faint fuzzy dot by the unaided eye. And you do have to get up

The comet will be best seen from dark sky sites. It will be easily seen in binoculars, and it races through the sky through some pretty territory (lots of binocular friendly open clusters).

Unfortunately Moonlight will significantly interfere after the 22nd. Although the comet will still be readily visible in binoculars, it will be difficult to spot with the unaided eye until the Moon wanes. Click the link for Printable maps comet 103P/Hartley.

Printable PDF maps of the Eastern sky at 10 pm ADST, Western sky at 10 pm ADST. For further details and more information on what's up in the sky, see Southern Skywatch. Cloud cover predictions can be found at SkippySky.


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