|Events during June
1st - Partial Solar Eclipse - Visible across eastern Asia, northern North America and Iceland.
See eclipse details.
12th - Mercury is in superior conjunction.
15th - Total Lunar Eclipse - Visible from South America, Europe, Africa, Asia and Australia.
See eclipse details.
21st - 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 21st. After
this, slowly at first, the days start getting shorter. For observers in the southern hemisphere, the days will start to get longer.
28th - Pluto - in oppostion in Sagittarius.
MOON: New - 1st, Full - 15th, Perigee - 367,190 kilometres - 12th, Apogee - 404,270 kilometres - 24th.
Mercury can be glimpsed just before dawn low in the east-north-east, during the first few days of June,
for observors in the tropics and southern hemisphere. Mercury then passes through superior conjunction
on 12th June and reappears in the evening sky, low in the west-north-west after sunset for the last few days of the month. The planet is not visible
this month from more northerly 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.
At magnitude -3.9, Venus remains visible low in the east-north-east before dawn for
observors in equatorial and southerly latitudes. By the end of June the planet will not be observable, even from those locations. Observors in northern
latitudes will have to wait until December for a true Venusian (evening) spectacle.
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, at magnitude +1.3, continues to be visible low in the morning sky before dawn.
For most of June it is visible only from the tropics and southern hemisphere but by the end of the month may be glimpsed from more northerly
latitudes. There is no opposition
of Mars in 2011.
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 continues to be a conspicuous early morning object, moving from
Pisces into neighbouring Aries during June and
brightening from -2.1 to -2.2 magnitude.
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 year
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 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 beomes visible as soon as darkness falls and is observable, in the constellation of
Virgo, until setting in the early morning hours. During June brightness decreases from +0.7 to +0.9 magnitude and
the angle at which the rings are displayed, as viewed from Earth, reaches its minimum for 2011 at 7.2º. On 14th June, Saturn reaches its second
stationary point after which it resumes direct motion.
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 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 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 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.
On 28th June Pluto is at opposition in the constellation of Sagittarius, at a distance of 4,643 million
kilometres (2,885 million miles) and at magnitude +14.
New moon: 1st
First quarter: 9th
Full moon: 15th
Last quarter: 23rd