SkyEye

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

January 2007

• 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.

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 are not so constrained, often moving far above or below the ecliptic.

Sun

Sagittarius -> Capricornus
The Earth makes its annual closest approach to the Sun on 3 January. The date of perihelion can range from New Year's Day to 4 January.

Comet C/2006 P1 McNaught

Scutum -> Aquila -> Sagittarius -> Capricornus -> Sagittarius -> Microscopium -> Indus
Discovered by Robert McNaught last 7 August on Siding Spring Mountain, this unexpectedly bright comet reaches perihelion on 12 January. Already zero magnitude and continuing to brighten, it can be seen either just before sunrise or after sunset but its tail may be swamped by the glow of the twilight sky. Northern hemisphere observers should look for it below Venus and Altair just after sunset as the comet is hugging the horizon and getting lower. Alternatively, look for it just before sunrise to the right of Altair but it will disappear below the horizon early in the month. Southern hemisphere observers will get their chance from mid-month when the comet begins to climb away from the Sun in the evening sky but it will be outbound by then and fading from view.

Mercury

Sagittarius -> Capricornus -> Aquarius
On the far side of the Sun from us, Mercury reaches superior conjunction on 7 January and thus is not readily observable until later in the month when it appears low in the southwestern sky after sunset. Viewers in the northern hemisphere will get the best look at this elusive planet this month and next.

Venus

Sagittarius -> Capricornus -> Aquarius
Venus is our "morning star" until early August. Found in the southwest after sunset, it rapidly gains altitude this month for northern hemisphere observers. As is the case with Mercury, viewers in the southern hemisphere will not get the best views of this inferior planet. Our twin planet will duck behind the Moon's disc on 20 January.

Mars

Ophiuchus -> Sagittarius
The red planet remains frustratingly difficult to see in the eastern dawn sky, rising just before of the Sun. It will be several months before Mars rises sufficiently ahead of the Sun to be free of the dawn twilight.

Jupiter

Ophiuchus
The largest planet in the solar system is this month's "morning star." Rising an hour before Mars at the beginning of the month, it is two hours ahead of its neighbour by the end and the most conspicuous object in the dawn sky.

Saturn

Leo
The ringed planet is up nearly all night as it heads toward opposition next month. On 6 January it is occulted by the Moon.

Uranus

Aquarius
Verging on the edge of naked eye visibility, this gas giant sets mid-evening so look for it in the west just after sunset. The Moon occults Uranus on 22 January.

Neptune

Capricornus
A small telescope is necessary to view the most distant planet in the solar system. However, with conjunction approaching early next month, it is probably too close to the Sun to observe.

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.

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 at Furman University.

The image of Hoag's Object in the SkyEye banner is courtesy of NASA and the Hubble Heritage Team (STScI/AURA). Discovered in 1950 by astronomer Art Hoag, this unusual ring galaxy is slightly larger than our own Milky Way. The blue ring is dominated by young, massive stars whilst the nucleus is comprised largely of older, yellower stars. Located 600 million light years away in the constellation of Serpens, Hoag's Object was photographed by the Hubble Space Telescope on 9 July 2001.

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Last modified on 31 December 2006