September Sky Notes
Written by John Stapleton
Image Credit: Starwalk
A Procession of Planets
After being lost in the light of the long summer evenings, the autumn sees the welcome return of all seven of the visible planets to our night skies. Albeit some of them are low in altitude and others begin rising towards midnight and beyond. These nights offer us the last views of Mars and Neptune before they become too faint for any serious observation, and our last view of the rings of Saturn before they fall edge-on to us and (almost) disappear from view for a time. The darker evenings will make fainter, interesting objects such as nebulae, star clusters and galaxies more easily visible, and the potential nova, T Corona Borealis, is still, yet to explode into view.
Sky Notes
Please note all times given in this article are in GMT so remember to add an hour to get the time in BST.
Sky Schedule
Sun: From the beginning to the end of the month the period of dark sky increases from 6.5 to 8.5 hours. The Autumnal Equinox, when night and day are of equal length, occurs on 27th. The longer period of darkness provides a good opportunity to view the summer constellations and the Milky Way that runs through them. The Milky Way is actually our view through the spiral arms of our Galaxy which we see as a faint band of light caused by millions of distant stars.
Mercury: Mercury is an early morning object seen low in the East before dawn during the first week of September. It is located against the background stars of Leo but is not well placed for observation.
Venus: Venus is also seen very low, this time in the western sky, rising around 7:00pm. It is a brilliant object which can be seen in the light evening sky and lies against the background stars of Virgo
Mars: Mars rises after 10:30 and is moving from Taurus into Gemini. The red planet is both small and faint at this time but still easily distinguished in a small telescope.
Jupiter: The largest planet precedes Mars into the Eastern sky and is seen against the background stars of Taurus. Jupiter is much brighter than Mars and so can be used as a guide to the red planet, and to Uranus which lies about the same distance on the other side of Jupiter. The coloured bands and zones on the surface of the planet can be distinguished with small telescopes as can the Great Red Spot, a colossal hurricane, greater in diameter than the planet Earth. The Galilean moons can be seen with a good pair of binoculars or a small (bird-spotting) telescope. DSLR images of the planet will also pick up the moons.
Saturn: The ringed planet can be found further South, against the stars of Aquarius. Saturn reaches opposition (closest point to the Earth and opposite the Sun in the sky) on 8th, The rings are now nearly edge-on from our point of view and the planet consequently appears fainter. Saturn’s largest moon, Titan, can usually be seen and because of the lack of glare from the rings, up to 5 other moons can be picked out using a moderate-sized telescope.
Uranus and Neptune: Uranus rises before Jupiter and is on the boundary between Taurus and Aries, close to the Pleiades star cluster. Neptune reaches opposition (due South in the sky and at its highest elevation) on 20th. At magnitude 7.7 it will require large binoculars or a small telescope to find it. Neptune displays a smaller and truly blue disc compared to that of Uranus although it will appear only as a bluish star to most small instruments.
Meteor Shower: There are no bright meteor showers due in September
Comet: There are no bright comets expected this month.
Lunar: The New Moon occurs on September 3rd with First Quarter on 11th, Full Moon then follows on 18th September when there will be a Partial Lunar Eclipse. A thin shadow will fall across part of the Moon at about 02:45am. and Full Moon on 29th. Third Quarter then follows on 24th.