Information provided by the National Astronomical Observatory (IGN, Development).
Home astronomical summer of 2012
The
summer of 2012, according to estimatations made by the National Astronomical
Observatory (National Geographic Institute - Ministry of Development),
will begin on Thursday June 21 1h 9m the Peninsular time, one hour less
in the Canaries. This
station, which is the longest of the year for the past few centuries,
will last 93 days and 15 hours, and end on September 22 with the
beginning of autumn.
From
the astronomical point of view, the skies of summer 2012 will be
dominated by the presence of Mars and Saturn in the first part of the
night. The
two planets in the sky will go closer to each other up to the August 17
a distance of about 3 degrees (6 times the diameter of the Moon). The
traditional meteor shower of the Perseids will happen to the August 12,
and his observation that this year will be better in 2011 to coincide
with the moon close to the waning phase. Moreover, there will be no eclipse of the Sun or Moon during this season
The beginning of summer
The
beginning of the seasons is given, by convention, for those moments
when the Earth is in a certain position in its orbit around the sun In
the case of summer, this position is given at the point of the ecliptic
in which the Sun reaches its northernmost position. The
day that happens, the Sun reaches its maximum declination North (+23 °
27 ') and for several days at noon maximum height does not change, and
therefore, this circumstance is also called solstice ("Quiet Sun") of summer. At this point in the southern hemisphere winter starts.
The summer solstice day longer corresponds to the year. About this time are the day when the sun rises earlier and on which comes later. An
unrelated circumstantial stations also occurs at this time: on the
aphelion, ie the day when the Sun and Earth are further apart over the
years. It
is this greater distance from the Sun cause the Earth to move more
slowly along its elliptical orbit during the summer (as known as
Kepler's third law) and therefore the duration of this season is
greater.
Possible date of early summer
The beginning of summer can be, at most, three different dates of the current schedule (from 20 to 22 June). Throughout the century will begin in summer 20 and June 21 (Spanish official date), with the onset of the 2096 early-morning and late onset of 2003.
Length of Day
If we call colloquially day duration of time between sunrise and sunset at a given location, next June 21 will be the longest day. For example, in Madrid this duration is 15 hours and 3 minutes, compared with 9 hours and 17 minutes that will last the shortest day (December 21). Note that there are nearly six hours of difference between the shortest day and longest. This difference is highly dependent on latitude, being zero in Ecuador and being extreme (24 hours) above the Arctic Circle. It is just above the northern polar circle where a few days a year (around June 21) is the phenomenon of the midnight sun, when the sun is visible above the horizon 24 hours a day. (In Antarctica it occurs around December 21).
Sunrise and sunset
You might think that the longest day of the year is also the day the sun rises earlier and put it later, but not so: this is because the Earth's orbit around the sun is not circular but elliptical because the Earth's axis is tilted in a direction that has nothing to do with the axis of the ellipse. This makes a sundial and our watches, based on a fictitious sun, are misaligned. The day the sun rises sooner the June 14, while the day when the sun sets later is June 27.
Distance from Sun
At this time there is also the maximum annual withdrawal (aphelion) between Earth and the Sun On this occasion, the maximum distance the next day will be July 5, the distance of just over 152 million km, about five million km more than in early January, when the distance from the Sun reaches its annual minimum.
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 and during the summer the number of sunspots reaches values between 73 and 97. 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 summer eclipses will not take place.
Night observation of the sky in summer
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 (19 July 17 August and 16 September), except when trying to observe the Moon itself.
Full moon
The first full moon of summer will be July 3, giving the following 29 or 30 days later. This summer will be two full moons: August 2 and August 31.
Visibility of the planets
As the morning star Venus and Jupiter will, and as evening star Mars and Saturn.
Meteor showers
If you do not have any telescope can observe meteor showers that occur occasionally. The two most intense during the summer are the Delta Aquarids, whose maximum rate occurs around July 30, the most famous summer of Perseids, which peak occurs around August 12.
Constellations
As for the fictitious groups of stars known as constellations around the North Star will be over night Cassiopeia, Cepheus, Cygnus, the Dragon and the two Bears. South East to West will be Pegasus, the Eagle, Corona Borealis and Coma Berenices. Near the horizon will be over night, some of the zodiacal constellations, the Virgin of Aquarius, the latter already near dawn. Among the brightest stars visible in this stage which constitute the "summer triangle": Altair (the Eagle), Deneb (in Cygnus) and Vega (in Lyra).
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 emission nebulae, such as Laguna, Omega or the Trifid, and planetary nebulae like the Ring in the constellation Lyra or the weights in the Raposa. 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.
