Dr. N. T. Jiwaji
ntjiwaji@yahoo.com
When a space rock
flew past Earth on at the end of last month at a distance of nearly six million
kilometers, we are told that it “just missed” us! This gives you a good idea about how large
distances are in space. The key point is
that the space rock was huge, nearly 3 kilometers in size. Had it come a bit closer you would not be
reading this article today since it could have been pulled in to collide with
Earth. Most of humanity passed the last
day of May in peaceful ignorance of the consequences. Scientists have been following this
particular space rock since it was first detected in 1998. After this close flyby, scientist will be
able to calculate its path far more accurately and be able to determine whether
it will hit Earth when it comes by again after 200 years. We await the verdict.
The origin of the
space rock is not very clear and its composition is also a mystery since it is
extremely black. It may be the remains
of a past comet that may have come too close to the Sun or it may have
originated from a broken rock from among the thousands of asteroids that circle
the Sun between the orbits of Mars and Jupiter.
Another
interesting asteroid in the asteroid belt is currently being followed excitedly
by astronomers since it is forming a longer and longer “tail” after collision with
another asteroid. The long “tail” of broken pieces forms a trail that orbits
the Sun. The study of this collision and
trail of pieces can help to explain the origin of the asteroid belt itself as being
pieces from a broken up planet.
With Jupiter now
out of view, Venus has brilliantly taken its place and shines this month at an
elevation of nearly 20 degrees above the western horizon at sunset. It will continue to rise to its highest
elevation of nearly 45 degrees by the beginning of November. This month, it provides a beautiful view on
Monday June 10 when a thin crescent Moon comes close to Venus and Mercury to
form a noticeable triangle in space.
Mercury is a
planet that never appears very high in the sky since its orbit is closest to
the Sun. This June, on Friday 14th, it will be at its highest elevation of 22
degrees above the sunset horizon. After
that, Mercury will fall rapidly lower in the sky and will be lost in the Sun’s
glare by the end of the Month.
While Mercury gets
lower in the sky, Venus rises slowly, so the two planets will meet in the sky
on Friday 21st June, at an elevation of 16 degrees above the western horizon at
sunset. If you use a telescope (carefully,
since you can destroy your eyes if, by mistake, you point it towards the Sun),
then you will see it in a crescent shape.
This is because Mercury has an inner orbit compared to Earth, so we see
it when the Sun is on its opposite side.
Saturn is almost
overhead towards the East, and it shines as a sharp steady point in the sky. Through a telescope the flat system of rings
is a beautiful sight well worth the effort.
Saturn is positioned in the leg of Virgo constellation. The Moon is New on June 8, First Quarter on
June 16, Full on June 23 and Last Quarter on June 30.
The sky map shows us that we can see nearly 18
constellations and asterisms in the night skies this month. Marked alphabetically from A to R these are,
from south to north, then east to west: A – Sagittarius the archer, B –
Scorpius, C – Ara the alter, D – Triangulum Australe, the
southern triangle, and E – the famous Southern Cross continuously pointing
south. F – is the False Cross, G – is
Vela, the sail, H – is the zodiacal constellation of Libra the scales of
justice and I – is the long Hydra the snake. J is Virgo the virgin while K – is Leo the Lion. L - is Cancer the crab while M – is Hercules,
N – is Bootes the herdsman and O – is the famous Big Dipper pointing north. P –
is Ursa Major, the big bear while Q – is Draco the dragon. R – is the Little
Dipper in Ursa Minor whose end star is the North Star but which we never see as
it is below the horizon.
Among the bright stars marked ‘m’ to ‘s’ on the map
are: ‘m’ – Alpha Centauri the closest
star at a distance of 4.3 light years and ‘n’ – is Beta Centauri. ‘o’ - is red
star Antares in the neck of Scorpius, ‘p’ – is Spica in Virgo while ‘q’ is the
third brightest star Aructurus (the first and second brightest stars are
respectively Sirius and Canopus
will have set in the south west by 8 pm). ‘r’ – is Regulus in Leo while ‘s’ –
is Procyon.
The full glory of the dense concentration of stars and dust
can be seen in the Milky Way which stretches across the southern skies from
southwest to southeast containing the constellations or asterisms C, D, E, F
and G. It runs parallel to the zodiacal
constellations A, B, H, J, K, L. June 21st is the Solstice, when the
Sun starts its journey back towards the Equator after completing its journey
north to the Tropic of Cancer. This day
marks the beginning of northern summers and southern winters.
END
Dar Es Salaam 
