SkyEye

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

July 2013

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	Mon
2	Tue	Pluto at opposition
3	Wed
4	Thu	Uranus at west quadrature
5	Fri	Earth at aphelion
6	Sat
7	Sun	Moon at the most distant apogee of the year
8	Mon	New Moon
9	Tue	Mercury at inferior conjunction
10	Wed
11	Thu
12	Fri
13	Sat
14	Sun
15	Mon
16	Tue	The First Quarter Moon occults first-magnitude star Spica: visible from the Central America and northwestern South America from about 01:30 UT.
17	Wed
18	Thu
19	Fri	Whilst taking a series of pictures of Saturn's rings, Cassini captures images of the Earth between 21:27 and 21:42 UT. Everybody wave!
20	Sat
21	Sun	Moon at perigee
22	Mon	Full Moon
23	Tue
24	Wed
25	Thu
26	Fri
27	Sat
28	Sun	Saturn at east quadrature
29	Mon	Last Quarter Moon
30	Tue	Mercury at greatest elongation west
30	Tue	The waning crescent Moon makes observing the Delta Aquariids a little difficult.
31	Wed

Coming up next month...

The ever-reliable Perseid meteor shower makes its annual appearance. The distant planet Neptune also reaches opposition later in the month.

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
Earth reaches its farthest point from the Sun on 5 July. The date of aphelion can range from 2 July to 6 July.
Mercury: Gemini
This planet vanishes from view at the beginning of the month as it keeps its appointment (inferior conjunction) with the Sun on 9 July. It soons reappears in the east before sunrise and is best seen at the end of the month as it reaches greatest elongation west on 30 July.
Venus: Cancer » Leo
The evening star makes for poor viewing in the northern hemisphere, never rising very high above the western horizon after sunset. However, it seems to leap upwards this month for southern hemisphere observers.
Mars: Taurus » Gemini
The red planet remains a difficult object, requiring an early start to find it low in the east before sunrise.
Jupiter: Gemini
Now a morning sky object, Jupiter appears low in the east just before sunrise.
Saturn: Virgo
On 28 July, Saturn is at east quadrature. It is at this time that the Saturnian system of planet, rings and satellites takes on a three-dimensional effect, with shadow effects at their most pronounced.
Uranus: Pisces
Uranus is a west quadrature on 4 July and is rising around midnight this month.
Neptune: Aquarius
This blue ice giant is approaching opposition next month and so it rises by early evening. However, a small telescope is necessary to view this most distant planet in the solar system.
Pluto: Sagittarius
A medium-sized telescope is necessary to see this fourteenth-magnitude former planet at opposition on the second day of the month.

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 one of the most detailed images ever created of our planet, 'Blue Marble Earth', showing North and Central America. This composite was put together from data gathered during four orbits of the Suomi NPP satellite. The spacecraft was launched in October 2011 and was renamed later that year in honour of Verner Suomi, the 'father' of satellite meteorology. The image is courtesy of NASA.