SkyEye

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

August 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	Mon	Jupiter at west quadrature
2	Tue	Moon at perigee
3	Wed
4	Thu
5	Fri	4 Vesta at opposition
6	Sat	First Quarter Moon
7	Sun
8	Mon
9	Tue
10	Wed
11	Thu
12	Fri
13	Sat	The Full Moon obliterates viewing of the famous Perseids (theoretical peak activity: between 01:00 UT and 13:30 UT).
14	Sun
15	Mon
16	Tue	Venus at superior conjunction
17	Wed	Mercury at inferior conjunction
18	Thu	Moon at apogee
19	Fri
20	Sat
21	Sun	Last Quarter Moon
22	Mon	Neptune at opposition
23	Tue
24	Wed
25	Thu
26	Fri
27	Sat
28	Sun
29	Mon	New Moon
30	Tue	Moon at perigee
31	Wed

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: Cancer » Leo
Mercury: Leo
The closest planet to the Sun is visible in the west after sunset early in the month (and is easier to spot from southern latitudes than northern) but is soon lost in solar glare as it heads towards inferior conjunction on 17 August. It reappears just ahead of the rising Sun at the end of the month.
Venus: Cancer » Leo
The "morning star" disappears from the east early this month as it heads towards superior conjunction on 16 August. It reappears at the end of the month very low in the west after sunset.
Mars: Taurus » Gemini
At the end of the month, the red planet passes near the fainter and yellower delta Geminorum or Wasat as it is traditionally known.
4 Vesta: Capricornus
Sixth-magnitude 4 Vesta reaches opposition on 5 August. It is the only asteroid to attain naked-eye visibility.
Jupiter: Aries
At west quadrature on the first day of the month, Jupiter is an inviting target for small telescopes. Quadrature is the best time to watch the interplay of planetary and satellite discs and shadows, giving a real 3-D effect. The largest planet in the solar system rises before midnight.
Saturn: Virgo
The ringed planet is setting earlier and earlier in the evening. Look for it in the west after sunset.
Uranus: Pisces
With opposition approaching next month, Uranus is up nearly all night, rising in the early evening.
Neptune: Aquarius
A small telescope is necessary to view the most distant planet in the solar system. Neptune is at opposition on 22 August but is eighth magnitude at best.

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.