Mercury - undergoes one of its best evening apparitions of the year during the first half of this month. When it reaches maximum eastern elongation on February 7, Mercury shines at magnitude -0.7 and is located 7 degrees to the lower right of Venus. It subtends 7", with a 53% illuminated disk, and is visible for more than 1.5 hours after the sunset. Mercury's apparent size increases by 1" as its phase decreases from 78% to 56% during the first week of February. A week later Mercury shrinks to a crescent and dims to magnitude 0.8. Not long afterwards the speedy planet disappears into the Sun*s glare.

Venus - is approximately 19 degrees above the horizon on the first day of February and 27 degrees on the last day of the month. Venus is 1 degree southeast of Lambda Aquarii (magnitude 3.8) on February 6.

Mars - is rising in the south-east just as the sky is brightening towards dawn, and it s not at all easy to see. It s moving steadily eastwards across the southerly constellations of Sagittarius and Capricornus, and at magnitude +1.4 it looks just like a moderately bright star. Its characteristic red colour will hardly be noticeable.

In the telescope, it shows a disc just 4 arc-seconds across; the colour should appear stronger, but it won t be possible to make out any detail.

Jupiter - Jupiter is coming up in the south-east much earlier than Mars. At the start of February it rises at about 4:30 am; by the end of the month, that becomes 3 am. By dawn, Jupiter is quite well up in the southern sky.

This month Jupiter is moving slowly eastwards in the constellation of Ophiuchus. In the adjacent constellation of Scorpius, look for the red-giant star Antares; it appears to the lower right of Jupiter. But at magnitude -2.0, the giant planet appears significantly brighter; it outshines all the stars.

Jupiter s four major moons can often be seen in binoculars, as tiny points of light in a straight line to either side of the planet. The outermost one, Callisto, can sometimes be glimpsed with the naked eye, especially in twilight, when the dazzle from the planet is reduced. Callisto will appear to the east of Jupiter around February 1st and 18th, and to the east around the 10th and 27th.

In the telescope Jupiter shows a disc about 35 arc-seconds across, with dark belts of cloud. The famous Great Red Spot may sometimes be seen as a faint pinkish hollow in the darker South Equatorial Belt. It should be near the centre of Jupiter's disc on the mornings of February 2nd, 4th, 7th, 9th, 11th, 14th, 21st, 23rd, 26th and 28th.

For detailed postions of Jupiter's Moons try this interactive javascript utility.

Saturn - reaches opposition on February 10 and is therefore visible for the entire night. Its rings span 46". Watch as the ring tilt increases to a 15 degree inclination from edge on.

This month Saturn shines at magnitude 0.0, its equatorial diameter is 20.2 arc seconds, and the ring inclination is -13.6 degrees. Titan (magnitude 8.4) passes north of Saturn on the nights of February 4 and February 20 and south of it on the nights of February 11 and February 28. Eleventh magnitude Iapetus, Saturn's unusual satellite, is located to the south of Saturn on the night of February 13.

The Cassini spacecraft continues its observation of Saturn and its many moons and rings. For the latest images from Cassini, see:

http://saturn.jpl.nasa.gov/home/index.cfm

For detailed postions of Saturn's Moons try this interactive javascript utility.

Uranus - located in Aquarius. During the first half of January, look for it 30 degrees up in the SW an hour after sunset. Uranus will be less than 1 degree SE of 3rd magnitude Lamba Aquarii during this time. At magnitude 5.9, Uranus can be glimpsed with the naked eye from a moderately dark site. Through a telescope, Uranus has a 3.4" greenish disc.

A finder chart for Uranus can be found on page 66 of the May issue of Sky & Telescope.

Neptune - can be located within 1.4 degrees of Venus just after sunset.

A finder chart for Neptune can be found on page 66 of the May issue of Sky & Telescope.

Pluto - is rising in ESE before dawn.

A finder chart for Pluto can be found on page 66 of the May issue of Sky & Telescope.

Eris (pronounced "EE-ris") - formerly known as Xena, 2003 UB313, and "the tenth planet"  is magnitude 19 in central Cetus, high in the south during evening.