Information provided by the National Astronomical Observatory (IGN, Development).
Autumn 2012
The
autumn of 2012, according to estimates by the National Astronomical
Observatory (National Geographic Institute - Ministry of Development),
will begin on Friday September 22 at 16h 49m Peninsular time, one hour
less in the Canaries. This station will last 89 days and 20 hours, and end on December 21 with the onset of winter.
From
the astronomical point of view, the sky during the fall of 2012 will be
initially ruled by Mars at the beginning of the night. As
we move through the station, Mars will be visible, and a very bright
Jupiter, coming soon will be visible in the evening until early
November. This planet will reach its closest approach to Earth on December 1. During
the fall of 2012, there will be a total solar eclipse (November 13) is
not visible from Spain, and a penumbral eclipse of the Moon (November
28) than in Spain will only be visible in its final stages.
On the other hand on Sunday October 28 will take place on time change, restoring the winter time.
The onset of autumn
The astronomical start of the stations is given, by convention, as the moment when the Earth passes through a certain position in its orbit around the sun In the case of fall, this position is from the center of the Sun as seen from Earth crosses the celestial Ecuador apparent motion to the south. When this happens, the length of day and night practically coincide, and therefore, this circumstance is also called 'autumn equinox'. At this point in the southern hemisphere spring begins.
Possible date of early fall
The autumn equinox may be, at most, four different dates (from 21 to 24 September). Throughout
the century will begin in autumn 22 and September 23 (Spanish official
date), being the early bird onset of 2096 and the later start of 2003. Variations
from year to year are due to the way that fits the sequence of years
according to the schedule (a leap, some not) with the duration of each
orbit of Earth around the Sun (known as the tropical year length).
Shortening of the day
This is the time of year when day length shortens faster. At
latitudes of the peninsula, the sun rises in the morning every day a
little later than the day before and we then put before the shortening
of the day being especially noticeable in the evenings. In short, these days the time that the Sun is above the horizon is reduced by almost three minutes each day.
Solar Activity
The Sun's activity is characterized by the presence on its surface blemishes, flares and prominences, and the earth, is seen in changes in the propagation of radio waves and a greater presence of polar auroras. This activity follows a period of about 11 years, and is associated with Sun's magnetic cycle we are now in Solar Cycle 24 began in December 2008 and is expected to reach its peak in May 2013. According to estimates by NOAA Space Weather Prediction Center in the fall the number of sunspots reaches values between 76 and 99. Graphs with the number of sunspots in recent years and predictions of the evolution of cycle 24 can be found in Space Weather Prediction Center.
Eclipses and related phenomena
Throughout the autumn there will be two eclipses. On 13 November a total solar eclipse will be visible in Australia, New Zealand, South Pacific, Antarctica and southern South America. This eclipse will be accompanied by a penumbral moon will be two weeks later, on November 28, and that in Spain we will see, with the inherent difficulty of such eclipses, in its final stages. The first contact with the penumbra at 13h 15m will (GMT), will peak at 15h 34m, the eclipse will end at 17h 51m.
Night observation of the sky in autumn
In every season there is an astronomical phenomenon of interest, predicted (such as eclipses) or not (such as new comets). It is usually preferable to make observations around the time of new moon (15 October 13 November and 13 December), except when trying to observe the Moon itself.
Full moon
The first full moon will fall on September 30, giving the following 29 or 30 days later. This fall will two full moons: October 29 and November 28.
Visibility of the planets
Jupiter will be visible from most of the night after dark and also the day will take place December 1st annual closest approach to Earth, reaching an angular diameter of 48 ". Saturn will be visible at night in early fall to be visible at dawn at the end of the season. All fall Ddurante Venus will be visible at dawn and dusk Mars.
Meteor showers
If you do not have any telescope can observe meteor showers that occur occasionally. The first major meteor shower of autumn is that of Draco, whose maximum is given to the October 8. Another popular meteor shower in winter is that of the Leonids, which occurs around November 17 and occasionally becomes very intense. Rain is usually the most intense of the Geminids, with a maximum rate occurs around December 13.
Constellations
As for the fictitious groups of stars known as constellations around the North Star will be throughout the night Swan, Cassiopeia, Ursa Minor and Giraffe. Ecliptic constellations are visible in this period of Capricorn to Virgo. As highlighted above the ecliptic Pegasus and Andromeda below, Whale and Orion and the stars Sirius and Procyon.
Observations with binoculars or small telescopes
With large binoculars or a small telescope, equipped with a suitable moon filter, you can see the relief on the Moon. To get a good view of it should go night after night watching as it grows the illumination of the moon, for so we can see new terrain accidents. When the night is darker for having a new moon, you can try to see the Andromeda galaxy, emission nebulae such as Orion or the star cluster Pleiades. With binoculars you can also see Jupiter's brightest moons (when visible) and can take a tour of the starry band that is the Milky Way.
Time Change
The time change occurs, as usual, at the beginning of the last Sunday in October. At three o'clock CET on Sunday October 28 will have to turn back the clock to the two (the two o'clock in the Canary Islands will be the one), so that this day will be, officially, one more hour.
