SkyEye

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

April 2010

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	Thu
2	Fri
3	Sat
4	Sun
5	Mon
6	Tue	Last Quarter Moon
7	Wed
8	Thu	Mercury at greatest elongation east
9	Fri	Apogee
10	Sat
11	Sun
12	Mon
13	Tue
14	Wed	New Moon
15	Thu
16	Fri
17	Sat	Moon occults the Pleiades: visible from around 06:00 UT in New Zealand and the nearby islands to the north and east.
18	Sun
19	Mon	Mars passes M44, the Beehive cluster.
20	Tue
21	Wed	First Quarter Moon
22	Thu	The waxing gibbous Moon does not interfere too badly with the Lyrids (theoretical peak activity: from 17:00 UT).
23	Fri	The Pi Puppids enjoy similar light conditions as the Lyrids (theoretical peak activity: from 22:00 UT but no activity is predicted this year).
24	Sat	Perigee
25	Sun
26	Mon
27	Tue
28	Wed	Full Moon
28	Wed	Mercury at inferior conjunction
29	Thu
30	Fri

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 » Aries
Barely visible from the southern hemisphere this month, the innermost planet of the solar system rises high above the western horizon after sunset on its way to greatest elongation east on 8 April. It then plummets back into the solar glare and a rendevous with the Sun on 28 April.
Venus: Aries » Taurus
As seen from the northern hemisphere, the "evening star" is rising rapidly above the western horizon.
Mars: Cancer
THe red planet passes by M44, the Beehive cluster, on 19 April and sets well after midnight.
Jupiter: Aquarius
The largest planet in the solar system rises in the dawn sky.
Saturn: Virgo
Opposition happened only last month so the ringed planet is above the horizon most of the night.
Uranus: Pisces
With conjunction only last month, this distant gas giant is still lost in the glare of the rising Sun.
Neptune: Aquarius
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.

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 SkyEye banner features a collision of galaxy clusters and is courtesy of NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara) and S. Allen (Stanford University). When MACS J0025.4-1222 was formed, gravity caused the ordinary matter in the colliding galaxy clusters to slow down whereas the dark matter, which at best interacts only weakly with itself, continued on its original course. Thus, this object provides both confirmation of the existence of dark matter and a further understanding of its properties. This image is a composite of Hubble Space Telescope and Chandra X-ray Observatory data where dark matter is coloured blue (mapped by Hubble using gravitational lensing techniques) and ordinary matter is coloured pink (mapped by Chandra detecting X-rays from gas heated by the collision).