|Events during October
|13th - Saturn is in conjuncton with the Sun.
29th - Jupiter at opposition in Aries.
30th - Summer Time ends and the clocks go backwards one hour (Spain and UK).
MOON: Full - 12th, New - 26th, Apogee - 406,435 kilometres - 12th, Perigee - 357,050 kilometres - 26th.
Meteor Showers during October
The Draconids meteor shower October 6th to 10th, maximum meteors
on the 8th between 19:00-21:00h.
WATCH OUT FOR THIS POTENTIAL SURPRISE PACKAGE OF THE YEAR! The comet Giacobini-Zinner currently has an orbital period of about six and
a half years. Depending on the influence of Jupiterīs gravitational pull on the comet, Earth may pass close to the descending node of the
cometīs orbit in early October. For an associated meteor shower to be observed, Earth must pass close to the node within 6 million kilometres
and within a relatively short time (ideally less than 100 days) before or after the comet has passed. It is not unknown for a Draconid meteor
count of 200 to be taken in 2 minutes.
On October 8th 2011, Earth passes close to the node 132 days before the comet but, because it also passes close to a group of old trails, there
is a chance of a significant outburst, as many as 800 slow-moving meteors per hour according to some forecasts. The waxing gibbous Moon in Aquarius,
less than 4 days from full will interfere.
The Orionids meteor shower October 16th to 31st - maximum meteors occurring from the 20th-22nd.
In the same way as the Draconids are associated with the comet Giacobini-Zinner and the Perseids,
seen in August, are associated with comet Swift-Tuttle, the Orionids are thought to be produced by material from Halley's comet.
With a Last Quarter Moon on the 20th, moonlight should not interfere at peak time with an expected hourly average of 20. The radiant of the Orionids is located
in the northeast of the constellation of Orion.
The best way to observe meteors is to lie outdoors in a reclining chair or sun-lounger. Try to take in as much of the sky as possible. When you see a meteor
mentally trace it backwards until you arrive at the radiant point.
Mercury passed through superior conjunction
at the end of September and remains unobservable until the middle of October when it beomes visible in the western sky after sunset. For observors in equatorial and
southern latitudes the planet will be visible to the south of due west in the evening twilight sky from mid-October onwards.
This evening apparition of Mercury is interesting because of the planetīs proximity to Venus towards the end of October and beginning of November.
The brilliant Venus is a useful guide to locating the fainter, and more elusive, Mercury.
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, magnitude -3.9, emerges into the western sky after sunset for observors in
equatorial and southerly latitudes.
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, brightening from +1.3 to +1.1 magnitude during October, continues to be visible as an
early morning object. By the end of October, Mars is rising at about midnight from northern temperate latitudes and a little later for those living further south.
The planetīs rapid apparent motion takes it from Cancer
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, in Aries at magnitude -2.9,
is at its brightest this month since it is at opposition on 29th October. It is therefore visible
throughout the night wherever the observor is located.
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 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 and passes
through superior conjunction on the far side of the Sun on 13th October. Consequently it is unobservable this 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 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.
Uranus remains in Pisces
with a magnitude of +5.7. Barely visible to the naked eye, it is easily located with binoculars.
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 is a morning object in Aquarius
visible in binoculars or a small telescope.
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.
First quarter: 4th
Full moon: 12th
Last quarter: 20th
New moon: 26th