Monthly Star Guide August 2013

Star chart for 15th August at 8.00 pm

Star chart August 2013

Moon phases

Moon-phases-2013.08-Aug

Those nights highlighted yellow are the best for viewing stars in the evening when the moon is a thin crescent or rises late.

Information on moon phases and times of sunrise and sunset can be accessed for any time of the year from Information on the drop down menu at the top of the page.

End of Ramadan

The moon will be in conjunction with the Sun at 21 h 52 min (GMT) on the 6th August.

Since Ramadan ends when the crescent moon is first seen in the evening sky after sunset that would be expected to happen the following evening, the 7th August.

Visibility, however, depends not only on the percentage of the moon surface lit up but also on its angular displacement from the Sun and the angle of the ecliptic with the horizon, the two factors determining the height of the moon above the horizon at sunset.

Wednesday August 7th 2013: The Moon sets before the Sun in northern parts of Asia, most of Europe and northern part of Canada (within the brown shaded area).

If the conditions are excellent,  the new crescent moon should be seen from most of South America, Polynesia and the Hawaiian Islands.

New moon 7th Aug 2013

Thursday August 8th 2013: The crescent moon should be visible from most of the world with the exceptions of northern Asia, most of Europe including the British Isles and northern Canada.  These areas will probably make their sightings the following day on Friday August 9th.

New moon 8th Aug 2013

For further discussion about sighting the Ramadan moon, take a look at the star blog from 2010: Ramadan Moon

Planets

Mercury was at its greatest elongation on the 30th of last month and is now returning towards the Sun and disappearing behind (superior conjunction) it on the 24th of this month. It is therefore best viewed at the beginning of the month an hour and a quarter before sunrise.

Venus remains resplendent in the evening sky at magnitude -4 and sets about an hour and a half after the sun.

Mars rises about two and a quarter hours before the sun. It lies in the constellation of Gemini where its brightness is less than that of either Castor or Pollux but its reddish hue makes it stand out. Its apparent diameter is very small (4″) which makes it difficult to study through a telescope.

Jupiter rises two and a half hours before the Sun on the 1st and over four hours before on the 30th, its brightness increasing to -2 by the end of the month, its apparent diameter 34″. As it rises in the sky, it becomes easier and easier to view. Note a beautiful alignment of Jupiter, Mars and Mercury in the morning sky of the 9th when there is not moon in the sky to disturb the view.

Saturn sets three hours after the Sun at the beginning of the month and two hours at the end but because of the low angle of the ecliptic at the moment, it still appears quite low in the sky and viewing is disturbed by the atmosphere.

Meteor Showers: Perseids

perseids_bruenjes

The maximum for the Perseids will occur on the 12th August when the moon sets at 9.41 pm leaving the rest of the night perfectly dark for viewing the spectacle of the falling stars, some of which will leave long bright traces in the sky, others can be brighter than Venus.

The meteors are a dust trace left from the Swift-Tuttle comet with an orbital period of 133 years which last swept past the Earth in 1992.

They are called the Perseids because the meters seem to fall from a point in the constellation of Perseus. They will be best seen after midnight when Perseus rises and when the rotation of the Earth is driving into the dust cloud.

See the latest star blog on meteors which is taken from an excellent article by David K. Lynch: Meteor Showers

 

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