|Events during February
The Moon: Full – 2nd, Last quarter – 10th, New moon – 17th, First quarter – 24th.
This snapshot shows Saturn close to the full Moon in the east at 23.00h on the 2nd February.
January through July are the best months to view Saturn during 2007. It is easily spotted as the pale golden planet rising early in
the evening as soon as it is dark. You can watch it rise high into the winter sky with the south side of the rings facing Earth. In July, Saturn will
dip lower in the sky and by early August it will be lost in the glare of the setting Sun. In September, Saturn will appear in the early morning sky
before dawn, rising earlier each month until the end of 2007.
The Earth and Sun passed through Saturn's ring plane in 1995 and 1996, providing a nearly edge-on view of the rings. From then the
ring tilt increased and opened wider to a maximum tilt of 27º in early 2003, and has since been decreasing. The ring tilt will continue to decreases
and close until 2009, when again there will be an edge-on view. This year's ring tilt angle varies from 15.4º down to 6.7º. Saturn is brighter this
year than it will be until 2015 due to slight dimming as the ring tilt becomes narrower and Saturn's distance from Earth increases.
Reaching opposition on February 10th, Saturn can be seen rising at sunset and setting near dawn. This extent of the rings will not
be seen again for several years to come, so look for Saturn near the Moon on the 2nd, shining at magnitude 0.0, with an equatorial diameter of 20.2
arc seconds, and a ring inclination of -13.6º.
The deep sky objects in this month´s snapshot, focused on Saturn, includes seven spiral galaxies. The objects are:
M44 (Praesepe / The Beehive Cluster) – an open cluster in Cancer at 3.7 magnitude.
M65 – a spiral galaxy in Leo at 9.3 magnitude.
M66 – another spiral galaxy in Leo at 8.9 magnitude.
M85 – a lenticular galaxy in Coma Berenices at 9.1 magnitude.
M95 – a spiral galaxy in Leo at 9.7 magnitude.
M96 – a spiral galaxy in Leo at 9.2 magnitude.
M98 – a spiral galaxy in Coma Berenices at 10.1 magnitude.
M99 – a spiral galaxy in Coma Berenices at 9.9 magnitude.
M100 – a spiral galaxy in Coma Berenices 9.3 magnitude.
M105 – an elliptical galaxy in Leo at 9.3 magnitude.
||Mercury is at greatest elongation of 18º on the 7th at –0.5 magnitude. On the 23rd the planet is at
inferior conjunction and then becomes a morning object but too close to the Sun to be observed.
The best times to observe Mercury are when it is an evening star in the spring and a morning star in the autumn. In midsummer the lighter skies make visibility difficult near the horizon.
||Venus in Pisces, brightens further to –4.0 magnitude and sets soon after 21.00h by the end of February.
The Moon is above on the 19th.
On the 8th June 2004, Venus was at inferior conjunction
and transited the sun. Transits of Venus are rare, taking place at greater
than 100 year intervals and usually in pairs. The last two transits of Venus were in 1874 and 1882. June's transit
began at 7.20h and lasted 6 hours until 13.20h, the total event visible from Europe as a small black disc crossing
the lower part of the sun from left to right. The next transit will be in late June 2012. After that, transits of Venus
won't occur again until 2117 and 2125.
Before and after inferior conjuction, when Venus is
the closest it comes to the earth, are the times at which the planet is most brilliant and can be seen setting or rising
4 hours after or before the sun. The dates of the next two inferior conjunctions are October 28th 2010 and October 26th 2018.
||Mars is at 1.3 magnitude in Capricorn. In morning twilight, the planet rises before 7.00h by the 28th.
The Moon is below on the 15th.
At opposition on the 28th August 2003, Mars was only 56 million kilometres from the earth. It showed a
disc of 25.1 seconds of arc across which is almost as large as it can ever appear. Mars started 2003 at 310 million kilometres from
the earth at 4.5 seconds of arc and 1.6 magnitude. By opposition it brightened 50 times to reach -2.9 magnitude but faded to 0
magnitude by December. Even to the naked eye Mars was a striking object in the summer and autumn sky, easily identifiable by its
reddish hue in an area of sky poor in bright stars. Mars will not be as close again for another 15 years.
These favourable oppositions occur every 15 years but other oppositions occur at average intervals of 2 years 2 months. In general Mars is observable every other year, being too close to the sun for favourable conditions during other times. Brightness at opposition varies from -1.0 to -2.9 magnitude, and when furthest from the earth it fades to 1.7 magnitude. The planet can be identified by its orange-red colour.
||Jupiter in Ophiuchus at –2.0 magnitude, rises about 3.30h by the end of February.
The Moon is below on the 12th.
Being 770 million kilometres from the sun, the difference in brightness between opposition and conjunction varies less than with Mars, from about -2.8 to -1.8 magnitude.
The 4 largest moons of Jupiter are easily visible through a small telescope, ranging from 4.6 to 5.6 in magnitude. The innermost, Io, takes 1.8 days to orbit the planet making its motion easily detectable within a few minutes.
||Saturn is in Leo at 0.0 magnitude, at opposition on the 10th and above the horizon all night. The full
Moon is closeby on the 2nd.
Saturn crossed the equator into the northern hemisphere in 1996 where it will remain until 2010 with the southern side of the ring system facing the earth. Because of its distance, its brightness varies little between opposition and conjunction but is affected by the huge ring system. Seen edge on the rings contribute little or no light.
Every 15 years the plane of Saturn's rings passes through the sun, illuminating first the north and then the south side. For a few days the rings are edge on to the sun. About the same time the earth passes through the ring plane and, depending on the earth's position this may happen just once or 3 times. During 1995/96 there was a triple crossing and the next will be 2038/39. The next single crossings will be in 2009 and 2025.
Saturn's largest moon, Titan, is visible in small telescopes orbiting outside of the ring system.
||Uranus in Aquarius, sets just after sunset by the end of February.
Brightness varies slightly reaching 5.6 magnitude at opposition. This is bright enough to see with the naked eye but identifying it against the stars is difficult.
||Neptune in Capricorn, is in conjunction with the Sun on the 8th and not visible during February.
Neptune has an average magnitude of 7.9 which varies little with changing distance.
||Never brighter than 13 magnitude, Pluto is only visible through powerful telescopes and we will therefore not be reporting on its position in the sky.|
Full moon: 3rd
Last quarter: 11th
New moon: 19th
First quarter: 25th
The Moon in 2007:
The Moon was seen unusually high and low in the sky during 2006 (see Moon). Although the extremities occurred last year, the Moon will still be seen very
high and very low each month this year, most noticeable around full Moon. It will be near full and high around the 2nd and 29th January, the 25th February
and the 24th March; and near full and low around the 1st and 28th June.
During each month of 2007, the Moon will pass through the Pleiades. This will mostly be in daylight but observable 01.00-04.00h 7th August,
0.00-03.00h 28th October and 22.00-01.00h on the 21st to 22nd December. Binoculars will give a clearer view.