Sky Notes for May 2013 with James Abbott #stargazing
May opens with Saturn near opposition, the point in its orbit where the Earth lies between the gas giant planet and the Sun. This means Saturn is also as its closest to us and is at its brightest. Even at this closest point for the year, Saturn is still over 800 million miles from Earth.
Seen with the unaided eye it appears as a yellowish bright object some 13 degrees to the left of Spica, the brightest star in Virgo. By mid-month Saturn is due South at 11.30pm BST and about 30 degrees in altitude. (Note: As a guide – If you hold your arm out, your fist will cover roughly 10 degrees of the sky.)
The famous rings of Saturn are now well presented to us and can be seen even with a good pair of binoculars. When the rings are “open” as they currently are, the planet’s brightness increases as the rings act like a mirror reflecting more of the Sun’s light back towards Earth. Unlike a real mirror though, the rings are actually made up of icy particles and ice boulders, orbiting the planet in a multitude of streams, all in a thin plane. As well as the rings there are over 60 Moons identified to date. These range from small bodies interacting with the ring system, up to Titan, which is slightly larger than Mercury, has a substantial atmosphere and would be classed as a planet if it was orbiting the Sun alone.
Saturn presents more Moons readily observable in typical amateur-sized telescopes than any other planet – five or perhaps six depending on aperture and conditions. Further information can be found in this article by Sky & Telescope.
Full Moon is in the early hours of the 25th when the Moon will slink just 18 degrees above the Southern horizon after local midnight.
On May 12th there is one last chance this year to see a close pass of Jupiter by the Moon in the evening sky. At around 9.30pm BST the thin new crescent Moon will be just 4 degrees from Jupiter low down in the Western twilight.
The waxing Moon from mid-month coincides with the onset of summer twilight and so the best opportunity to observe in a dark sky will be the first half of the month, after which astronomical twilight will persist until the last week of July as the Sun remains at 18 degrees or less below the Northern horizon.
On 10th May it is just about dark by 11pm BST and the last of the winter constellations are bowing out in the North West. Last to slip towards the horizon is Gemini, the 2 bright twin stars almost parallel to the horizon. Gemini is a constellation that has a shape in the sky that resembles its name and when in the West, with a bit of imagination you can see two figures standing side by side. Turning around and looking to the North East the summer constellations are rising with Cygnus, The Swan, becoming prominent. Cygnus really does look like a swan in flight with its wings outstretched.
James Abbott is an astronomer, NEAS member and CfDS Regional Information Officer.
Posted on 1 May, 2013, in Astronomy News, Observing News, Popular Science and tagged gemini, jupiter, moon, opposition, saturn. Bookmark the permalink. Comments Off on Sky Notes for May 2013 with James Abbott #stargazing.