October Night Skies
By Dr. N. T. Jiwaji
ntjiwaji@yahoo.com
News about new planet discoveries has injected new ideas about where planets can be found around stars other than our Sun. A planet with four suns, about 5,000 light years away, was recently discovered by amateur astronomers on a home computer. They used the planet-searching website www.planethunters.org which presents data from the Kepler Spacecraft. Since there is so much data coming in, it is easiest for a human being recognize the signs of a planet circling other stars.
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Another recent discovery was of a planet that is circling
three stars in the Alpha Centuri system which is the next closest star to us
after our Sun at a distance of only 4 light years away. The mere fact of
discovery of a planet so close to us has raised the excitement of the
possibility of even travelling to such a planet. The fact that planets have
been found to exist around multiple star systems has raised the chances of finding
more planets and indeed finding life other than our own.
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(http://news.nationalgeographic.com/news/2012/10/121017-alpha-centauri-new-planet-science-space-udry/)
In terms of space travel, a very modest spacecraft Voyager
1, launched in 1977 to explore our Jupiter and Saturn has broken all records in
performance. It is still working, sending us data that shows that it has now
entered interstellar space. The count rate of cosmic particles hitting its
sensors has dropped to only 5 percent of that when it was inside the boundary
of our solar system.
This shows that it has now left the extreme edge of our
solar system (the Kuiper belt) which is more than 18 billion kilometres from us
(more than 100 times the Earth-Sun distance). With higher technology the
possibility of travel to the nearest stars appears to be humanly possible!!
A good weekend activity awaits us this weekend from midnight
of Saturday 20th to dawn of Sunday 21st. A night-out that
can be made even more exciting by the possibility of seeing a significant
number of meteors, some which may even blow up as bolides. There will be no moon, so even faint meteors will
be seen. The meteors will appear to be
originating from the Orion constellation, near its red giant star Betelgeuse.
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The sky currently shows the majestic huge trapezium shaped
Orion Constellation which will be overhead by sunrise. Within the Orion
Constellation, you will see its red giant star BETELGEUSE, and next to it is
the brightest star Sirius, and on the other side the bright planet Jupiter, all
these three forming a line. Next to Sirius on the south you will see another
bright star Canopus, which is the second brightest star in the sky.
By 4:30 am dawn of Sunday, bright Venus will also be rising
in the East. So lay a blanket on your terrace and lie down and wait patiently
to be dazzled by a meteor every two or three minutes and make as many wishes as
the meteors you see!! At dawn, our overhead sky is moving head on into the
Earth's orbit so ideal for picking up the particles and dust left behind by
Haley's comet during its past passes close to Earth, the last of which was in
1986.
Among the evening planets, the red planet Mars is close to
the red giant star Antares in the Scorpio constellation and the pair is close
to the western horizon at 7 pm. Watch the two red points changing positions due
to the movement of the planet.
Mercury is high in the western sky at sunset close to the
western horizon. Mercury is closest to the Sun so it is most difficult to see
by most observers all over the world. However at the moment it is high enough
at more than 20 degrees elevation at sunset for us to be able to see it with
our naked eyes. It will each maximum height of 22 degrees at the end of the
month and will rapidly descend after that.
Jupiter has now entered the early night skies and at the
moment it rises in the eastern horizon at around 10 pm. It will remain with us in
the evening skies until May next year. So plan your astronomy activities to
observe this majestic planet with its four Galilean moons shifting positions
when viewed through even a modest telescope.
The Moon was new on 16th and has ushered in the
holy month of pilgrimage for Muslims who celebrate Idd ul Hajj 10 days later,
so the Idd day can be expected on 26th October. First quarter will
be on 22nd October when the Moon will be in half shape and best for
viewing craters through binoculars or telescope. Full Moon will be on October
29.
This is a month of galaxies because if you are well away
from city lights you might be able to make out patches of brightness that are
made by our closest neighbouring galaxies, the Small Megallenic Cloud, which is
about 37,000 light years away can be seen close to the horizon towards the
south. Many smaller galaxies are in the grip of gravity of the Milky Way and
they circle as satellite galaxies. The number of such galaxies has now grown to
20 with the discovery of four new satellite galaxies. This may not be the end
as more continue to be discovered.
Satellite galaxies are dwarf galaxies which are a few
hundred light-years across rather than being hundreds of thousands of
light-years which is the size of a normal galaxy. The large number of such
small galaxies that surround the main galaxy has made scientists rethink the
properties of dark matter which is a mysterious matter which we cannot see but
which is known to make up more than 90 percent of our universe. Galaxies are
thought to form from clumping in dark matter but if there are so many of them
then the particles of dark matter must be cool enough to form clumps. At the
moment dark matter is understood to be made up of fast moving (hot) particles
so if there are so many dwarf galaxies, the dark matter must be much cooler
than initially thought.
The Andromeda galaxy can be seen again close to the horizon
in the north. It is a spiral shaped galaxy similar to our Milky Way galaxy and
is about 2.2 million light years away. This makes the Andromeda galaxy the most
distant object that we can see with the naked eyes. Try to locate these two
galaxies using the star map.
The eastern sky has two “birds”; one to the northeast, where
you will see the Cygnus with its body and wings making a wide cross, while in
the southeast you will see the smaller bird Grus with its head twisted sideways.
Try to become familiar with the brightest stars by their names and relative
locations.
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