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Mercury difficult to observe

The moon begins the month as a thin sliver visible in the early morning, alongside Mercury. The latter will be a tough observation, as the sun brightens the sky just as Mercury clears the horizon. By Feb.
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The moon begins the month as a thin sliver visible in the early morning, alongside Mercury.

The latter will be a tough observation, as the sun brightens the sky just as Mercury clears the horizon. By Feb. 6, the moon will be in its new phase, sharing the sky with nearby Jupiter in the early evening. Feb. 11, the Pleiades share the spotlight with the first-quarter moon (seven days old). The loose cluster just to the left (east) is the Hyades in Taurus, The Bull. And, a little further east is mighty Orion. The moon is full in the early morning of Feb. 18; Saturn is within eight degrees Feb. 21 and the asteroid Vesta is within one degree Feb. 27 - an occultation in the South Pacific and Antarctica.

The moon averages 400,000 kilometres, ranging from a minimum at perigee of 356,000 kilometres, to a maximum at apogee of 406,000 kilometres. Vesta orbits in the asteroid belt between Mars and Jupiter; its distance from the sun averages 353 million kilometres.

Mercury, as mentioned above, is a difficult sight as it is quickly absorbed in the sun's glare early in the month. Mercury's distance from Earth ranges from 77 million and 222 million kilometres.

Venus shines brightly in the early morning sky, rising about 6 a.m. and gradually getting lower and lower with each passing day. Watch for the sliver of moon hovering beside the bright "Morning Star" on the morning of Feb. 28. Venus's distance ranges from 38 million to 261 million kilometres.

Mars is behind the sun and not visible. Mars' distance is between 55 million and 400 million kilometres - right now near the latter.

Jupiter, while progressing steadily eastward, appears to move to the west, as Earth moves about its orbit much more quickly. This is termed "retrogression" or "retrograde motion." The giant planet appears to be heading for a disappearing act behind the sun. By the beginning of May, we will have moved eastward far enough in our orbit that the sun will be out of the way and Jupiter will be a morning object. Jupiter is between 893 million and 964 million kilometres away.

Saturn rises in the east about midnight, crossing the sky to disappear from view in the southwest in the morning twilight. Saturn's distance is between 941 million and 1.5 billion kilometres.

Uranus lies in the same general direction as Jupiter, but is much further away - its current distance is almost 21 times further away than the sun, varying between 2.57 and 3.16 billion kilometres.

Neptune, the most distant of planets, is in the constellation Aquarius, closing in on an encounter with the sun. Just like Jupiter and Uranus, it appears to be moving westward, when, in fact, it is us here on Earth doing the rapid motion. Neptune's distance varies between 4.3 billion and 4.68 billion kilometres.

Far out in the distant reaches of the so-called Kuiper Belt are the dwarf planets like Pluto, Eris, Makemake and Haumea. The most distant, Eris, is 14.4 billion kilometres away; Pluto averages 7.5 billion kilometres. More than 1,000 Kuiper Belt Objects (KBOs) are known and it is estimated that over 70,000 could exist.

- James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000. He is editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal, and is the society's national secretary.

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