Tuesday, 13 September 2011

The Night Sky September 2011 | Jodrell Bank Centre for Astrophysics

The Night Sky September 2011 | Jodrell Bank Centre for Astrophysics


'via Blog this'


A Cassini image of Jupiter . Nasa
Jupiter rises soon after 9pm BST in mid september and so, by midnight, will be ~30 degrees above the eastern horizon.   It shines at magnitude -2.7 in the constellation Aries, the Ram.   It is now well worth observing (if you do not mind staying up late or getting up early!) and, with an angular size of ~47 arc seconds, a small telescope will easily show the equatorial bands and the Galilean moons.   In contrast to Saturn which is moving towards the lower part of the ecliptic (and hence will not reach as high an elevation when due south), Jupiter is moving towards the higher part of the ecliptic and so, in the next few years, will be a superb object to observ

 A montage of the Solar System


The planet Saturn. Cassini - Nasa
Saturn.  At the very beginning of September, Saturn may still just be visible low (at an elevation of ~5 degrees) in the Southwest 40 minutes after after sunset in the constellation Virgo, some 7 degrees to the west of Spica.   But by the middle of the month it will be lost in the sun's glare.   It has a magnitude of +0.9.   Compared to early last year, its apparent brightness has now increased as the rings have opened out again - now tilted at +8 degrees from edge on.   The plus sign indicates that we are seeing Saturn's north pole.   The rings span an angular size of ~32 arc seconds - over double the 15 arc seconds of the planet's disk.   Given a small telescope it may be be possible (given the low altitude) to see Saturn's brightest moon, Titan. 


Messenger image of Mercury Nasa
Mercury passed between the Earth and the Sun (inferior conjunction) on the 16th August and emerged into the pre-dawn sky towards the end of August.   On the 1st of September it is just 4 degree above the eastern horizon an hour before dawn and reaches its peak brightness , at magnitude -0.3, on the 3rd when at greatest western elongation.  
It lies close to Regulus, in Leo,on the 8th and 9th but then rapidly moves towards the Sun and becomes lost in its glare until it passes behind the Sun (superior conjunction) on the 28th of the month.
See highlight above.


Mars showing Syrtis major.
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa
Mars.   On the 1st of September, Mars,shining at magnitude +1.4 lies in Gemini just 1 degree north of the star Delta Geminorum and has risen to an elevation of ~30 degrees at sunrise so can be easily seen in the pre-dawn sky just north of East.   Its angular size is just 5 arc seconds mid month and so one is unlikely to see any detail on its salmon-pink disk.   Having moved into Cancer, on the last morning of the month it lies just to the right of the Beehive Cluster,M44, which should make a very nice telescopic view.
See highlight above. 


Venus showing some cloud structure
Venus passed behind the Sun on the 15th of August - called superior conjunction - and will reappear to view just above the horizon 25 minutes after sunset at the very end of the month.   Even with a magnitude of -3.9, binoculars may still be needed to spot it - but do not use them until after the Sun has set!

Radar Image of Venus
Radar image showing surface features

Find more planetary images and details about the Solar System: The Solar System

The Stars

The Evening September Sky

September Sky
The September Sky in the south - early Sept:~11pm, late Sept:~10pm
This map shows the constellations seen towards the south in late evening. To the south in early evening moving over to the west as the night progresses is the beautiful region of the Milky Way containing both Cygnus and Lyra. Below is Aquilla. The three bright stars Deneb (in Cygnus), Vega (in Lyra) and Altair (in Aquila) make up the "Summer Triangle". East of Cygnus is the great square of Pegasus - adjacent to Andromeda in which lies M31, the Andromeda Nebula. To the north lies "w" shaped Cassiopeia and Perseus.

The constellations Lyra and Cygnus

Cygnus and Lyra

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