SkyEye

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

April 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	Tue
2	Wed	Moon occults Neptune: visible from the central section of South America from about 8:00 UT.
3	Thu
4	Fri
5	Sat
6	Sun	New Moon
7	Mon	Moon at perigee
8	Tue
9	Wed
10	Thu	Jupiter at west quadrature
11	Fri
12	Sat	Moon occults Mars: visible from northeastern Canada, Greenland and Iceland from about 5:00 UT.
12	Sat	First Quarter Moon
13	Sun
14	Mon
15	Tue
16	Wed	Mercury at superior conjunction
17	Thu
18	Fri
19	Sat
20	Sun	Full Moon
21	Mon
22	Tue	The light of the waning gibbous Moon badly hampers observations of the Lyrid meteor shower.
23	Wed	The Pi Puppid meteor shower is similarly spoiled by moonlight this year.
		Moon at apogee
		Moon occults first-magnitude star Antares: visible from southern Australia and New Zealand from about 17:00 UT.
24	Thu
25	Fri
26	Sat
27	Sun
28	Mon	Last Quarter Moon
29	Tue	Moon occults Neptune: visible from the northern half of Australia, the eastern part of Indonesia and Papua New Guinea from about 19:00 UT.
30	Wed	A cross-quarter day occurs midway between equinoxes and solstices.

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: Pisces -> Aries
Mercury: Pisces -> Cetus -> Pisces -> Aries -> Taurus
Mercury dives towards the horizon and its date with the Sun on 16 April. It will be visible from the northern hemisphere in the sunset sky by the end of the month.
Venus: Aquarius -> Pisces -> Cetus -> Pisces
A very low "morning star" continues to sink in the eastern sky. Although still easy to spot from the southern hemisphere, northern observers are finding it increasingly difficult to observe Earth's nearest neighbour.
Mars: Gemini
Appearing as a brilliant red "star" in the west at nightfall, Mars sets just as Jupiter rises in the east.
Jupiter: Sagittarius
Because Jupiter is at western quadrature on 10 April, this is a particularly good time to observe its Galilean satellites. A small telescope will show the interesting interplay of shadows - planet on satellites, satellites on planet - which is emphasized during quadrature. The largest planet in the solar system rises around midnight.
Saturn: Leo
The ringed planet is particularly well-placed for viewing in the evening. Look for it near the first-magnitude star Regulus before they both set in the early morning hours.
Uranus: Aquarius
This distant gas giant rises in the early morning at about the same time that Saturn sets.
Neptune: Capricornus
A small telescope is necessary to view the most distant planet in the solar system. It rises about an hour before its outer solar system neighbour Uranus and is occulted by the Moon twice this month, once on the 2nd and again on the 30th.

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.