SkyEye

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

May 2011

The Calendar

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	Sun
2	Mon
3	Tue	New Moon
4	Wed
5	Thu
6	Fri	Lack of moonlight makes this is a very favourable year for observing the Eta Aquariids.
7	Sat	Mercury at greatest elongation west
8	Sun
9	Mon
10	Tue	First Quarter Moon
11	Wed
12	Thu	Early risers this month will be treated to a gathering of the planets Mercury, Venus, Mars and Jupiter as they cluster close together low in the east before sunrise. These four planets appear near each other in the sky all month but are most tightly packed together mid-month.
13	Fri
14	Sat
15	Sun	Moon at perigee
16	Mon
17	Tue	Full Moon
18	Wed
19	Thu
20	Fri
21	Sat
22	Sun	Neptune at west quadrature
23	Mon
24	Tue	Last Quarter Moon
25	Wed
26	Thu
27	Fri	Moon at apogee
28	Sat
29	Sun
30	Mon
31	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: Aries » Taurus
Mercury: Pisces » Cetus » Aries » Taurus
Southern hemisphere observers get the best views of this elusive planet as it climbs high in the east before sunrise. It reaches greatest elongation west on 7 May and then heads back towards the horizon.
Venus: Pisces » Aries
The "morning star" is disappointingly low in the dawn sky when seen from the northern hemisphere but is easily seen from southern latitudes. It is steadily losing altitude as the month wears on.
Mars: Pisces » Aries
The red planet is slowly pulling away from the Sun and rises about the same time as its much brighter neighbour Jupiter.
Jupiter: Pisces
The largest planet appears near Mercury, Venus and Mars in the morning sky shortly before sunrise, with a particularly tight grouping occuring mid-month.
Saturn: Virgo
At opposition last month, the ringed planet is visible for most of the night, setting at dawn.
Uranus: Pisces
The most distant planet that can be seen with the naked eye rises early in the morning, about an hour before Jupiter.
Neptune: Aquarius
A small telescope is necessary to view the most distant planet in the solar system. It reach west quadrature on 22 May and rises just after midnight.

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.

The SkyEye banner features the beautiful planetary nebula NGC 2818. A planetary nebula is a glowing shell of gas surrounding a dying star. When a star begins to run out of fuel and expands into a red giant, the outer layers of the star are expelled into space, enriching the surrounding area with the heavy elements manufactured by the parent star. The remaining hot stellar core ionises the ejecta, causing it to glow for a few tens of thousands of years. Eventually the star fades away and nebula is no longer visible. This image was taken by the Hubble Space Telescope in November 2008 and is courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA). The red colour represents nitrogen, green represents hydrogen and blue represents oxygen.