Royal Astronomical Society of New Zealand Uranus and Neptune in 2008

Finder chart for Uranus and Neptune during 2008. Detailed charts for paths of Uranus and Neptune during 2008.

Positions of Uranus and Neptune during 2008.

Uranus is in the constellation Aquarius throughout 2008, while Neptune is in Capricornus.

Neptune is in conjunction with the Sun on February 11. In 2008 Neptune passes just south of the Sun. Uranus is in conjunction 26 days later on March 8. It will pass about half a degree to the south of the Sun.

The planets are too close to the Sun to observe for about a month either side of their conjunction date. When they become visible following conjunction, it is only briefly at first to the east in the morning sky before the onset of twilight. They will rise about 4 minutes earlier each day, 2 hours a month, and so become visible for longer during the night until opposition, when they are on the opposite side of the Earth to the Sun.

Opposition dates are approximately 6 months after conjunction, August 15 in the case of Neptune while Uranus is at opposition on September 13. At opposition the planets rise close to the time of sunset and set close to the time of sunrise, so are in the sky all night. They are due north (or south from the northern hemisphere) at close to local midnight.

Following opposition they will be rising before sunset and setting before sunrise and so become well placed for viewing in the evening sky until the end of the year.

Neptune reaches a stationary point on May 26 and again on November 2. The corresponding dates for Uranus are June 27 and November 28. Between these dates the planet will apparently be moving in a retrograde sense through the stars, that is towards the west rather than towards the east. The apparent backwards motion is due to the faster moving Earth overtaking the outer planets, which actually maintain a steady movement in an easterly direction around the Sun.

The magnitudes of the two planets only vary by about 0.2 during the year. At its brightest, for a month either side of opposition, Uranus has a magnitude of 5.7, making it faintly visible to the unaided eye from a dark site. Neptune's magnitude is about 7.8, so is readily visible in binoculars.

A series of occultations of Neptune by the Moon occur throughout 2008. None of these are observable from New Zealand, the events in January and March taking place near to midday. One is visible from the northern half of Australia before sunrise on April 29. During the second half of 2008 the occultations become visible from parts of the northern hemisphere.

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