August Night Skies Over Tanzania
By Dr. N. T. Jiwaji
ntjiwaji@yahoo.com
Two planets,
Mars and Saturn, and a star Spica struggle for position in the western sky this
month, half way up the sky.. Since April
this year, after a short stay in Leo constellation, the red planet Mars has
been moving stealthily eastwards across the background stars towards Virgo
constellation. It is now in its
pro-grade (normal, west to east) movement across the skies and is close to and
below the Saturn-Spica pair. By August 14,
it will be exactly in line between Saturn and Spica. Ater that it will continue eastwards leaving
the Saturn-Spica pair well behind.
This is the
best time to see distinct changes in the sky where stars normally maintain
their relative positions for thousands of years. There is an almost day by day change, and in
fact, between 12th and 18th you will see distinct difference
each night as the trio change shape, from triangle now, to a straight line on
14th, to a more and more stretched triangle on the other side. By August 20, a beautiful crescent Moon joins
the trio and the shapes become even more interesting to watch with Saturn, Mars
and Moon forming a perfect straight line on August 21.
As we watch
Mars from the Earth, keep in mind that a new spacecraft has just landed on its
surface on August 6, after an 8 month, 600 million kilometer journey. The car-sized rover, named Curiosity, will
spend the next two years exploring the surface of the red planet for sign of
life.
The
south-west sky is also the home of a dense collection of stars that rises
straight up from the horizon into the sky, in a bright path called the Milky
Way. The numerous stars in this Milky
Way are actually part of our own flat spiral galaxy known by the same name. This bright path in the sky this August shows
so many stars and brightness because you are watching it from within the Milky
Way Galaxy, towards its center and along its flat plane; hence our line of
sight cuts through myriads of stars. On
either side of the Milky Way, the sky will be distinctly barren of stars since
there are not many stars that cut our line of sight across the thinner part of
our flat spiral galaxy system.
Two easily
identifiable constellations are also in the south western skies this
month. High in the sky is Scorpio whose
stars form an immediately recognizable shape of a scorpion.
Lower down
towards the horizon you will see two very bright stars pointing vertically down. The upper very bright star is Alpha-Centauri
(or Rigel Kent) which is the closest star to us (after the Sun), at a distance
of about 4 light years - meaning that light, travelling at 300,000 km/hr, takes
4.4 years to reach us, yet this is the closest star!!
The bright vertical
pair points towards another prominent constellation, called the Southern Cross,
with a shape of a kite. The long
diagonal of the kite points directly towards the South. Be careful that since it is now almost
parallel to the horizon, after 9 pm it will be exactly parallel to the horizon
and hence will point towards the south celestial pole which is about 6 degrees
above the horizon for us in Tanzania.
In the early
morning skies in the east, watch Jupiter rise at 1:30 am (for example while
watching the Perseid meteors on the night of August 12/13). Venus rises two
hours later around 3:30 am. By sunrise, Mercury has joined the show, forming a
straight line with Jupiter, Venus and the rising Sun. This line is the path, only along which you
can see planets, since they orbit the Sun in an almost completely flat plane.
Among the evening
constellations are the long, winding Scorpio mentioned above, and Sagittarius
the archer. The Southern Cross
(described above) lies on its side close to the southwestern horizon and points
south. In the north you can make out Cygnus
the swan as a cross with the bright Deneb (A) at its tip. Among the bright stars you can try some with
famous names. These are, from west to
east, Spica (B) in constellation Virgo, Arcturus (C), Alpha (D) and Beta
Centauri (E) the two bright stars in the southern skies that point to the
Southern Cross, the red star Antares (F) in the neck of Scorpio, Vega (G),
Altair (H) and Deneb (A) all in the north and Fomalhaut (J) just rising in the
east at 8 p.m
On night of 12/13
August for three hours after midnight you can observe the peak of the Perseid
meteor shower. About 10 meteors (falling
stars) per hour are expected to be seen and will seem to be originating in the
region of the Perseus constellation in the north east. A crescent Moon rises at 2:45, so can spoil
the viewing of smaller meteors.
Bright space
craft that can be seen this month is the Chinese Thiangong Space Station on
August 13, when it will rise from the north-west horizon at 7:29 pm and will
rise high in the zenith skies to about 80 degrees and will disappear in
suddenly at 7:32 pm when it enters the Earth’s shadow. On 15th August 15, it will rise
from the north-west horizon at 6:46 pm and will rise to about 50 degrees in the
south west and will set in the south east five minutes later at 6:51 pm.
The
International Space Station (ISS) will be seen early next month on September 4,
5 and 7, so visit www.heavens-above.com for exact times, and www.astronomyintanzania.or.tz
for further details.
END
This post was written by: Author Name
Your description comes here!
Get Free Email Updates to your Inbox!
Post a Comment