SkyEye

Welcome to SkyEye, your guide to this month's celestial events.

September 2008

All times and dates are given in Universal Time (UT).
Nightly darkness estimates are calculated for 45° N and 30° S.
Like total solar eclipses, lunar occultation events can be seen only from limited regions on Earth (and sometimes not at all if the occultation takes place during daylight hours). However, the Moon will appear close in the sky to its "target" for some hours either side of the actual occultation, regardless of where you are.

Date		Event
1	Mon
2	Tue
3	Wed
4	Thu	Saturn at conjunction
5	Fri
6	Sat
7	Sun	Moon occults first-magnitude star Antares: visible from eastern Australia, New Zealand, the south Pacific and western South America from about 1:00 UT.
		First Quarter Moon
		Moon at apogee
8	Mon
9	Tue
10	Wed
11	Thu	Mercury at greatest elongation east
12	Fri
13	Sat	Uranus at opposition
14	Sun
15	Mon	Full Moon: The Full Moon nearest to the September equinox is commonly called the "Harvest Moon".
16	Tue
17	Wed
18	Thu
19	Fri
20	Sat	Moon at perigee
21	Sun
22	Mon	Last Quarter Moon
22	Mon	Equinox
23	Tue
24	Wed
25	Thu
26	Fri
27	Sat
28	Sun
29	Mon	New Moon
30	Tue

The Solar System

The word planet is derived from the Greek word for "wanderer." Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies including comets, are not so constrained, often moving far above or below the ecliptic.

Sun: Leo -> Virgo
The solar north pole is most inclined towards the Earth early this month. An equinox occurs on Earth on 22 September. The word equinox means "equal night" so that on this day, the (centre of the) Sun spends an equal amount of time above and below the horizon everywhere on the planet.
Mercury: Virgo
The closest planet to the Sun is at greatest elongation east on 11 September. It remains stubbornly close to the western horizon after sunset when seen from the northern hemisphere but soars high into the evening twilight for observers in the south, even getting above Venus in the sky. Mercury disappears from view late in the month for northern viewers but remains visible into October from southern hemisphere vantage points.
Venus: Virgo
The "evening star" stays close to the western horizon when seen from the northern hemisphere but for southern observers, Venus gets appreciably higher in the sky as the month progresses.
Mars: Virgo
The red planet sets soon after the Sun. It has two close encounters with Mercury, early and late in the month, and is seen near Venus mid-month. Look for Mars near the first-magnitude star Spica at the end of the month.
Jupiter: Sagittarius
The largest planet in the solar system sets about midnight.
Saturn: Leo
At conjunction on 4 September, the ringed planet reappears in the morning sky, rising just before the Sun at the end of the month and visible in the dawn twilight.
Uranus: Aquarius
At opposition on 13 September, this gas giant is up all night. It is just visible to the naked eye if the skies are very dark.
Neptune: Capricornus
A small telescope is necessary to view the most distant planet in the solar system. It sets in the early morning.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union (IAU) recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time	Northern Hemisphere	Southern Hemisphere
1730 hours (1830 hours summer time)	45° N	30° S
1930 hours (2030 hours summer time)	45° N	30° S
2130 hours (2230 hours summer time)	45° N	30° S
2330 hours (0030 hours summer time)	45° N	30° S
0130 hours (0230 hours summer time)	45° N	30° S
0330 hours (0430 hours summer time)	45° N	30° S
0530 hours (0630 hours summer time)	45° N	30° S

For More Information...

Consult our online glossary for non-technical explanations of many of the astronomical terms used in these pages.
Blue moons, eclipses, the dates of Easter and much more can be found at the Interactive Astronomy Pages.
For more information about the objects and events described in SkyEye, visit these astronomy-related sites.

Credits

Much of this information can be found in this month's issue of your favourite amateur astronomy magazine available in your local bookshop. Another excellent source is the current edition of the Astronomical Calendar by Guy Ottewell and published by the Universal Workshop at Furman University.

The image of the variable star V838 Monocerotis in the SkyEye banner is courtesy of NASA, ESA and the Hubble Heritage Team (STScI/AURA). Located 20,000 light years away in the constellation of Monoceros, V838 Mon temporarily brightened in early 2002. The reason for this outburst is not understood. The resulting light echo, the light from the stellar explosion illuminating the dust surrounding the the star, was captured by the Hubble Space Telescope in October of that year.