|Events during March
· 14th - Mercury is at superior conjunction.
· 17th - Uranus is in conjunction with the Sun.
· 20th - The spring equinox, when the Sun crosses the equator into the northern hemisphere.
· 22nd - Saturn is in oppostion in Virgo.
· 28th - Clocks go forward 1 hour for Summertime.
· The Moon: New - 15th, Full - 30th.
Apogee (406,540 kilometres) - 12th, Perigee (361,880 kilometres) - 28th.
Mercury passes through superior conjunction
on March 14th, after which it quickly moves east of the Sun. By the end of the month Mercury is visible in the western sky after sunset for observors in the northern
hemisphere. Magnitude decreases from -1.4 to -0.9 during the last week of March.
The best times to observe Mercury in the northen hemisphere 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.
Remaining at magnitude -3.9, Venus continues to draw away from the Sun and, by the end
of the month, is visible in the early evening western sky after sunset. Its northerly declination (the angular distance of an object in the sky from the
) means that the period of visibilty is longer for more northerly observors.
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, in Cancer
until its 2nd stationary point on March 11th after which it resumes
direct motion. At 249.2 million kilometres (154.8 million miles) from the Sun, Mars is at aphelion
on 31st March. Its distance from Earth on the same date is 150.5 million kilometres (93.5 million miles). Magnitude decreases from -0.6 to +0.2 during March.
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 until 2018.
These favourable oppositions occur every 15 or 17 years but other oppositions occur at average intervals of 2 years 2 months during
which time the planet makes a complete circle of the Earth. 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.
As in 2003, Mars comes nearest to the Earth at oppositions at the end of August. At these times it can be brighter than Jupiter,
although low in the sky in Aquarius for northern observors. In the northern hemisphere, the planet may be better seen at oppostions during autumn and winter months
when it is higher in the sky.
Jupiter was in conjunction with
the Sun at the end of February and so will be unobservable until the last week of March. At that time it can be seen low in the eastern sky before dawn for
observors in the southern hemisphere.
Varying from 603 (at its closest) to 770 million kilometres from the sun, the difference in brightness between opposition and conjunction varies less than
with Mars, from about -2.9 to -1.8 magnitude. Always a bright planet, Jupiter comes to opposition a month later each year, moving approximately from one zodiacal
constellation to the next.
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 remains in Virgo, at +0.6 magnitude,
moving retrograde through opposition
on March 22nd. At opposition Saturn is 1,272 million kilometres (790 million miles) from Earth. The angular width of the rings has decreased further to about 3º.
Saturn moves more slowly than Jupiter and can remain in the same constellation for several years. The brightness of the planet depends on the
aspect of its rings, as well as its distance from Earth and the Sun.
The planet 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 is in conjunction with the Sun on the 17th.
Brightness varies slightly, reaching a maximum of +5.6 magnitude at opposition. This is bright
enough to see with the naked eye but identifying it against the stars is difficult. At closest approach, Uranus is 2,856 million kilometres (1,775 million miles)
Neptune has an average magnitude of 7.9 which varies little with changing distance. At its closest,
Neptune is 4,341 million kilometres (2,697 million miles) from Earth.
No longer an offical planet and never brighter than +13 magnitude, Pluto is only visible through powerful telescopes.
Last quarter: 7th
New moon: 15th
First quarter: 23rd
Full moon: 30th