|Events during May
|4th/5th - the maximum of the Eta Aquarid meteor shower falls this night, when
small pieces of Halley´s comet burn up in Earth´s atmosphere. However, strong
moonlight will drown out all but the very brightest shooting stars.
13th - JUPITER in conjunction with the Sun.
20th - SUN - an annular solar eclipse.
27th - MERCURY in superior conjunction.
MOON: Full - 6th, New - 20th, Perigee - 356,955 kilometres - 6th,
Apogee - 406,450 kilometres - 19th.
4th/5th May - The Moon is below Saturn with Spica (the brightest star in Virgo) lying between them.
5th/6th - The Moon is full and at perigee on the 6th May. At perigee the Moon is at its closest to
Earth and consequently looks bigger and brighter than usual. A full Moon at perigee is known as a super moon.
8th - In the early hours, the Moon is to the left of Antares (a red supergiant in Scorpio).
22nd - The crescent Moon makes a lovely pairing with Venus.
28th - Mars lies to the upper left of the First Quarter Moon and Regulus, the brightest star in Leo,
to its upper right.
29th - The Moon is to the left of Mars.
31st - The Moon lies below Saturn and Spica.
Mercury is on view before dawn in the east-north-eastern twilight sky, for observors in the tropics and southern hemisphere,
during the first two weeks of May. From more northerly latitudes the planet is not visible this month.
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.
Venus commences May as a prominent object in the south-western evening sky, shining at -4.5 magnitude
and setting four hours after the Sun in northern temperate latitudes, and two hours after the Sun in the tropics and more southerly climes. Venus draws very rapidly in
towards the Sun as May progresses and may be lost in the bright dusk twilight by the end of the month.
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. 2004's transit lasted 6 hours, 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 on 5th June 2012.
After that, transits of Venus won't occur again until 2117 and 2125.
Because Venus is seen against the solar disk, the transit can be viewed from anywhere on the Earth where the Sun is above the horizon at the time of transit.
The 2012 transit can be seen in full from Eastern Asia, the South-east Pacific Ocean (including New Zealand and central/Eastern Australia), the North-western
USA (Alaska) and North-western Canada (the Sun being above the horizon throughout). For much of the inhabited world, however, the transit is already in
progress at sunrise or sunset so it is not seen in its entirity. Observers in Portugal, South-western Spain, Western and South-western Africa and the
Southern and Eastern regions of South America will not see the event because the Sun is below the horizon. At latitudes north of 67° North, the Sun
is above horizon throughout the day, hence the entire transit is visible.
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.
Mars, in Leo, continues to fade, from 0.0 to +0.5 during May,
as its distance from Earth increases. The planet is visible in the southern sky as soon as night falls and sets in the early morning.
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 is in conjunction with the Sun on May 13th and is
not visible in northern temperate latitudes during this month. At magnitude -2.0, Jupiter may be glimpsed by the end of May low in the east-north-eastern twilight sky before
dawn by observors in the tropics.
After spending the past six years in the southern skies, Jupiter moved north of the celestial equator on February 5th 2011 to spend the next six years
in northern skies.
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 of Jupiter´s 60+ moons are easily visible through binoculars or 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 fades slightly from +0.3 to +0.5 during May. It is visible in the south-south-east as darkness falls
and is observable for most of the night moving retrograde in Virgo.
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 remained until 2010 with the southern side of the ring system
facing 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 last single crossing was in 2009 and the next will be in 2025.
Saturn's largest moon, Titan, is visible in small telescopes orbiting outside of the ring system.
Brightness varies only slightly, reaching a maximum of +5.6 magnitude at opposition. Although this is
bright enough to see with the naked eye, identifying it against the stars can be 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.
Full moon: 6th
Last quarter: 12th
New moon: 20th
First quarter: 28th