|Events during June
|4th - MOON - a partial lunar eclipse
5th/6th - VENUS in Inferior Conjunction
5th/6th - VENUS transits the face of the Sun
20th - SUMMER SOLSTICE - For observers in the northern hemisphere, the sun lies high in the sky during the day and not far below the horizon at night,
giving long twilight hours and short nights. The Summer Solstice, when the Sun reaches its most northerly point over the Tropic of Cancer, is on the 20th. After
this, slowly at first, the days start getting shorter. For observers in the southern hemisphere, the days will start to get longer.
29th - PLUTO at opposition in Sagittarius
MOON: Full - 4th, New - 19th, Perigee - 358,480 kilometres - 3rd,
Apogee - 405,790 kilometres - 16th.
3rd/4th June - The Moon is near Antares (a red supergiant in Scorpio).
17th June - In the dawn sky, the thin crescent of the Moon is next to Jupiter with Venus rising to the lower left.
18th June - Just before sunrise, the thin crescent Moon is to the left of Venus.
21st June - In the evening sky, the narrow crescent Moon lies below Mercury.
24th June - The Moon is close to Regulus, the brightest star in Leo.
25th/26th June - The Moon is close to Mars.
28th June - The Moon lies to the left of Saturn and Spica the brightest star in Virgo.
Mercury is approaching greatest eastern elongation
in July, and so is visible in the north-western evening sky
during the last three weeks of June for observors in equatorial and southern latitudes. The planet is not suitably placed for observation from northern temperate latitudes
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 passed rapidly through inferior conjunction
on 5th/6th June when it was seen in a rare transit across the face of the Sun. If you missed this one you have to wait
more than 105 years for the next! Following inferior conjunction, Venus moves swiftly into the morning sky before dawn. For observors in equatorial and southerly
latitudes, the planet may be glimpsed low in the twilight sky shortly before sunrise from the middle of June onwards. By the end of the month, from these latitudes,
the planet will be rising over two hours before the Sun and located quite close to the fainter Jupiter in the dawn twilight sky - Venus at -4.4 and Jupiter at -2.0
magnitude. The phase of Venus will have increased to 16% by the end of June. Unfortunately Venus remains inconveniently
low for observors in northern temperate latitudes this month.
On the 8th June 2004 and 5th/6th June 2012, 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. Prior to that, the last two transits of Venus were in 1874 and 1882. Transits of Venus won't occur again until 2117
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 is visible in the south-western sky as soon as darkness falls and sets around 1am. Its
direct motion carries the planet from Leo into
Virgo on June 21st. Mars fades from +0.5 to +0.8 magnitude during the month.
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, at -2.0 magnitude, is a conspicuous object in the early morning sky for observors in
equatorial and southerly latitudes but observors further north will probably not be able to see the planet until the second half of June. Now moving
directly in Taurus, Jupiter passes south of the
Pleiades star cluster in mid-June. On 17th June, the waning crescent Moon will be close to Jupiter in the
dawn twilight sky. By the end of the month, the much brighter Venus will lie in the same area of sky but lower down closer to the horizon.
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 Jupiterīs 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 begins June moving retrograde in
Virgo but after reaching its second stationary point on June 25th, it resumes direct motion. Saturn fades from +0.5 to
+0.7 magnitude during the month.
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.
Pluto reaches opposition on 29th June in the constellation of
Sagittarius. At a distance of 4,674 million kilometres (2,904 million miles), Pluto is visible only
through a moderate-sized telescope.
No longer an offical planet and never brighter than +13 magnitude, Pluto is only visible through powerful telescopes.
Full moon: 4th
Last quarter: 11th
New moon: 19th
First quarter: 27th