SkyEye

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

September 2007

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	Sat	It is a poor year to see the Alpha Aurigid meteor shower because of light from the waning gibbous Moon.
2	Sun	2 Pallas at opposition
3	Mon
4	Tue	Jupiter at east quadrature
4	Tue	Last Quarter Moon
5	Wed
6	Thu
7	Fri
8	Sat
9	Sun	Uranus at opposition
10	Mon	Moon occults first-magnitude star Regulus: visible from India and central Asia.
10	Mon	Moon occults Saturn: visible from the Indian Ocean.
11	Tue	The New Moon partially eclipses the Sun
12	Wed
13	Thu
14	Fri
15	Sat	Moon at apogee
16	Sun
17	Mon	Mars at west quadrature
18	Tue	Moon occults first-magnitude star Antares: visible from the southern oceans and the Antarctic.
19	Wed	First Quarter Moon
20	Thu
21	Fri
22	Sat
23	Sun	Equinox
24	Mon
25	Tue
26	Wed	Full Moon: the Full Moon nearest to the September equinox is popularly known as the "Harvest Moon" in North America.
27	Thu
28	Fri	Moon at perigee
29	Sat	Mercury at greatest elongation east
30	Sun

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 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 23 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: Leo -> Virgo
The closest planet to the Sun is at greatest elongation east on 29 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.
Venus: Cancer -> Leo
Although very bright in July, Earth's twin reaches its highest magnitude of the year this month, a brilliant -4.6. The "morning star" rises high in the east for northern viewers and climbs, albeit more slowly, from observers in the southern hemisphere.
2 Pallas: Pegasus
A small telescope is necessary to see this ninth-magnitude object at opposition on the second day of the month.
Mars: Taurus -> Gemini
The red planet reaches west quadrature on 17 September, passing close by M1, the Crab Nebula at about the same time. Telescopes reveal that the planetary disc displays a distinctly shadowed edge at this time. This zero-magnitude object is best viewed in the morning before dawn.
Jupiter: Ophiuchus
Jupiter is at east quadrature on 4 September. Quadrature is always an excellent time to view this planet through a telescope, as the interplay of shadows (planet on satellites and vice versa) is at its most pronounced. The largest planet in the solar system takes over duties as "evening star" and is found low in the west at dusk, setting by mid-evening.
Saturn: Leo
The ringed planet climbs rapidly above the eastern horizon in the morning hours before sunrise. It is occulted by the nearly New Moon on 10 September.
Uranus: Aquarius
At opposition on 9 September, this gas giant is up all night.
Neptune: Capricornus
A small telescope is necessary to view the most distant planet in the solar system. It sets just as Venus rises.

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 Hoag's Object in the SkyEye banner is courtesy of NASA and the Hubble Heritage Team (STScI/AURA). Discovered in 1950 by astronomer Art Hoag, this unusual ring galaxy is slightly larger than our own Milky Way. The blue ring is dominated by young, massive stars whilst the nucleus is comprised largely of older, yellower stars. Located 600 million light years away in the constellation of Serpens, Hoag's Object was photographed by the Hubble Space Telescope on 9 July 2001.