Mercury

Mercury remains well placed in the morning sky during the first half of May for observers in the tropics and Southern Hemisphere. It is visible towards the east-north-east just before sunrise. The planet increases in brightness from mag. 0.0 on May 1st to mag. –1.0 on May 17th as it moves closer to the Sun in the sky.

For Northern Hemisphere observers, Mercury is poorly positioned in May. Despite a reasonable separation from the Sun at the start of the month, it rises only about half an hour before the Sun from London, England. For the remainder of the month, it remains close to the Sun and difficult to observe.

The planet reaches superior conjunction on May 27th and perihelion on May 29th. At perihelion it is located only 0.307495 AU (approx. 46 million km or 28.6 million miles) from the Sun.

Venus

Venus begins the month as a brilliant evening star, shining at mag. –4.7, setting four hours after the Sun in Northern temperate latitudes and nearly 2 hours for observers in the tropics and the Southern Hemisphere. On May 6th, a nice conjunction occurs when Venus passes only 49 arcminutes from mag. 1.7 star Elnath (beta Tauri). With a mag. difference of about 6, Venus appears more than 250 times brighter than Elnath!

The planet then draws rapidly towards the Sun as the month progresses and by the last week of May will be difficult to pick out against the bright evening twilight.

Mars

Mars has now completed its latest retrograde motion and is now moving direct in Leo. It is visible as soon as night falls and sets in the early hours of the morning. The planet has been moving back and forth in Leo for some time, but now its again moving eastwards the motion of the Red planet against the background stars is noticeably quick. At the beginning of the month Mars is only a few degrees from Regulus, the brightest star in Leo, by the end of the month the distance has more than doubled.

Position of Mars in Leo during May 2012 - pdf format

Mars shines at mag. 0.0 with an apparent diameter of 10 arc seconds on May 1st. However, the rapid increase in distance between Mars and the Earth is starting to take its toll; the mag. reduces by months end to 0.5 and the apparent size to 8 arc minutes. Consequently, seeing details with a small telescope may be difficult, although the northern polar cap should be visible at the end of the month.

Jupiter

Jupiter is in conjunction with the Sun on May 13th and is not easily visible this month.

Saturn

Saturn reached opposition last month and is still well placed for observation during May. The planet is moving retrograde in the constellation of Virgo just north of bright star Spica. At mag. 0.3, Saturn is brighter than mag. 1.0 Spica and appears more yellowish compared with blue-white Spica.

Position of Saturn in Virgo during May 2012 - pdf format

Through a telescope Saturn looks fantastic, the rings are tilted at 14 degrees and are a wonderful sight whatever size instrument you have. On May 4th and 31st, the Moon forms a nice triangle with Saturn and Spica.

Uranus

Uranus is a mag. 5.9 morning object but not easily visible from Northern temperate regions. Observers located in the tropics and Southern hemisphere fair much better with the planet visible up to four hours before sunrise on May 31st.

During May, Uranus crosses the boundary from Pisces into Cetus.

Neptune

Neptune is also a morning object and like Uranus, is much better placed when viewed from the Southern Hemisphere or the tropics. The planet is located in Aquarius and shines at mag. 7.9. From the Northern hemisphere it may be spotted an hour or so before sunrise at the end of the month. For Southern hemisphere observers, Neptune is visible as a morning object during May and rises around midnight on May 31st.

Solar System Data Table - May 2012

	Date	Right Ascension	Declination	Mag.	Size	Illum. (%)	Distance (AU)	Constellation
Sun	5th May 2012	02h 49m 46.3s	16d 18m 15.9s	-26.7	31.7'	100	1.009	Aries
Sun	15th May 2012	03h 28m 50.1s	18d 54m 28.2s	-26.7	31.6'	100	1.011	Taurus
Sun	25th May 2012	04h 08m 51.1s	20d 58m 47.0s	-26.7	31.6'	100	1.013	Taurus
Mercury	5th May 2012	01h 28m 59.9s	06d 29m 41.3s	-0.3	6.1"	70	1.103	Pisces
Mercury	15th May 2012	02h 34m 32.3s	13d 28m 48.8s	-0.9	5.4"	86	1.241	Aries
Mercury	25th May 2012	03h 56m 02.4s	20d 28m 03.5s	-2.1	5.1"	99	1.320	Taurus
Venus	5th May 2012	05h 23m 38.5s	27d 49m 06.8s	-4.7	39.9"	23	0.418	Taurus
Venus	15th May 2012	05h 32m 57.1s	27d 21m 54.0s	-4.6	46.8"	14	0.356	Taurus
Venus	25th May 2012	05h 25m 27.9s	25d 56m 11.7s	-4.3	53.7"	05	0.311	Taurus
Mars	5th May 2012	10h 34m 28.2s	11d 03m 34.9s	0.1	9.6"	91	0.974	Leo
Mars	15th May 2012	10h 43m 48.6s	09d 46m 22.2s	0.2	8.9"	90	1.052	Leo
Mars	25th May 2012	10h 55m 48.2s	08d 13m 59.3s	0.4	8.3"	89	1.132	Leo
Jupiter	5th May 2012	03h 15m 46.3s	17d 15m 45.2s	-2.0	32.9"	100	5.998	Aries
Jupiter	15th May 2012	03h 25m 22.4s	17d 52m 43.6s	-2.0	32.8"	100	6.010	Taurus
Jupiter	25th May 2012	03h 35m 01.3s	18d 27m 37.5s	-2.0	32.8"	100	6.002	Taurus
Saturn	5th May 2012	13h 35m 46.0s	-07d 01m 19.5s	0.3	18.9"	100	8.775	Virgo
Saturn	15th May 2012	13h 33m 17.4s	-06d 48m 17.9s	0.3	18.8"	100	8.846	Virgo
Saturn	25th May 2012	13h 31m 12.0s	-06d 37m 56.8s	0.4	18.6"	100	8.943	Virgo
Uranus	5th May 2012	00h 25m 50.4s	02d 02m 10.4s	5.9	3.4"	100	20.854	Pisces
Uranus	15th May 2012	00h 27m 30.6s	02d 12m 43.8s	5.9	3.4"	100	20.741	Cetus
Uranus	25th May 2012	00h 28m 59.1s	02d 21m 58.3s	5.9	3.4"	100	20.609	Cetus
Neptune	5th May 2012	22h 20m 13.2s	-10d 58m 35.5s	7.9	2.3"	100	30.294	Aquarius
Neptune	15th May 2012	22h 20m 45.4s	-10d 55m 51.0s	7.9	2.3"	100	30.130	Aquarius
Neptune	25th May 2012	22h 21m 05.4s	-10d 54m 15.9s	7.9	2.3"	100	29.962	Aquarius