08-03-2008 Great stretch in the evenings (Article 127)

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Simon Kenny
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Location: Shannon, Co. Clare, Ireland

08-03-2008 Great stretch in the evenings (Article 127)

Post by Simon Kenny » Fri Jan 02, 2009 4:36 pm

Great stretch in the evenings (Article 127)

At this time of the year when meeting somebody you will often hear the conversation opener ‘great stretch in the evening’ instead of the usual ‘awful weather’ or ‘grand and dry’ or some other weather related comment. It is an optimistic expression and looks forward to the brighter sunnier days of spring and summer.

If you are interested in looking at the night sky then it means the opposite i.e. shorter nights and having to wait later each evening until the sky is dark enough to view what the heavens have on show. But, for March, anything you wish to see in the night sky is available at very sociable hours.

Let us do a quick run down on the ‘old reliables’ during March. First the Moon, have a look to the west about 20º above the horizon at 7 p.m and you should see a 2.3 days old new Moon (known as a waxing Moon). The sky will not be quite dark and only 6% of the Moon’s disc will be illuminated by the Sun. The Moon will be nicely positioned on 15 Mar at 9 p.m. between planet Mars (which will be 10º in the 3 o’clock direction) and the bright stars Castor and Pollux which will lie 10º in the 10 o’clock direction. On 21 Mar at 10 p.m. looking due SE at 22º above the horizon the Moon will be full, meaning the entire disc will be illuminated by the Sun and will be 14.9 days old.

Planets Uranus, Neptune, Pluto Mercury, Venus and Jupiter will all be relatively close to the dawn horizon during March and you would need to be observing around 5 a.m to spot them. They are dangerously close to the Sun and we always advise against using telescopes and binoculars when the Sun is either above or close to the horizon — instant blindness can occur.

That only leaves Saturn one of the most rewarding objects to observe in the night sky. Saturn always has the ‘wow factor’. To find it on 1 Mar at 10 p.m. look SE about 40 º up from the horizon and it will be the bright ‘star like’ object under the constellation Leo. At 10 p.m. during March it will gradually creep higher, getting to 49º and appearing nearer to a South direction.

Saturn takes a little over 29 years to complete one full orbit of the Sun. The spectacular system of rings that make it so attractive are aligned with its equator, which is tilted by 27 º from Saturn’s orbital plane. This means that as Saturn trudges around its 29 year elliptical lap of the Sun we see its ring system from different angles during this cycle. ‘Trudge’ is not exactly a fair description of its orbital speed which is 9.64 kms. per second! It’s just its sheer distance from the Sun (average of 895 million miles). The diagram below helps to explain why we see the ring system from different angles. Actual Earth- based photographs (in each corner of the diagram) correspond with various points of its orbit.

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