SkyEye

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

July 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	Apogee
2	Fri	C/2009 R1 (McNaught) at perihelion
3	Sat
4	Sun	Last Quarter Moon
5	Mon
6	Tue	Aphelion
7	Wed
8	Thu	Moon occults the Pleiades: visible from around 05:40 UT in southeastern Brazil.
9	Fri
10	Sat
11	Sun	A total solar eclipse is visible from the South Pacific, Easter Island and southernmost parts of South America.
11	Sun	New Moon
12	Mon
13	Tue	Perigee
14	Wed
15	Thu
16	Fri
17	Sat
18	Sun	First Quarter Moon
19	Mon
20	Tue
21	Wed
22	Thu
23	Fri
24	Sat
25	Sun
26	Mon	Full Moon
27	Tue
28	Wed	Apogee
28	Wed	The waning gibbous Moon, just two days past the full phase, washes out the Delta Aquariids.
29	Thu	Apogee
30	Fri
31	Sat

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: Gemini » Cancer
The Earth reaches its farthest point from the Sun on 6 July. The date of aphelion can range from 2 July to 6 July.
Mercury: Gemini » Cancer » Leo
Observers in southern latitudes continue to be favoured as Mercury reappears early in the month and eventually rises quite high above the western horizon. Look for it near Regulus on 27 July, the closest appulse of a planet and a first-magnitude star this year.
Venus: Leo
The southern hemisphere is the place to be to watch the "evening star" continue to rise ever higher above the western horizon. In contrast, Venus appears to sink toward the horizon when viewed from the north. Like its fellow inner planet, Venus also passes close by the first-magnitude star Regulus, albeit on 10 July.
C/2009 R1 (McNaught): Gemini » Cancer » Hydra
Robert H. McNaught, famous for his discovery of C/2006 P1 McNaught, found this icy visitor in September 2009 from images taken at Siding Spring Observatory in Australia. At perihelion on 2 July, this naked eye object will pass between the two brightest stars in the constellation Gemini a few days later. However, it will probably be lost in the Sun's glare for most of July. Because of its trajectory, it is unlikely that viewers from the southern hemisphere will be able to see this comet as a naked eye object but it might be visible in binoculars at the end of the month.
Mars: Leo » Virgo
The red planet is setting ever earlier in the evening. Look for it in the west after sunset.
Jupiter: Pisces
This gas giant rises late in the evening.
Saturn: Virgo
Saturn sets as Jupiter rises.
Uranus: Pisces
This faint planet, on the edge of naked-eye visibility, rises just ahead of its much brighter companion Jupiter.
Neptune: Aquarius
A small telescope is necessary to view the most distant planet in the solar system. With opposition occurring next month, Neptune rises in the east shortly after sunset.

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).