Transit of Venus
6th June 2012
VENUS
A VEILED PLANET
Amitabh Pandey
At times bright star is seen in the morning…
… and at other times in the evening
Early Greeks called the ‘evening star’ Phosphoros the
“Bringer of light” and ‘morning star’ Hesperos meaning
“Star of the evening”.
For about 9 months
Phosphoros remains in
eastern sky and then
Hesperos appears in the
western sky for about
same duration and then
repeat again. By the time
of Pythagoras in 6th
century BC it was resolved
that both stars are same
planet. Greek Named this
planet after goddess of
love Aphrodite. Roman
named it Venus after their
goddess of love.
In India this brightest planet
is named after ‘guru’ or
teacher of the Asuras,
Shukracharya, the Shukra
meaning ‘pure’, ‘clear’.
Probably some keen Greek astronomer observed Venus
regularly and it was moving every day relative to the
back ground of the star like other planets.
Its backward (retrograde) and forward (prograde) motion is
most noticeable and…
…Venus changes its brightness more than any other planet. To
explain it, it was suggested that its distance form the earth
changes! It means it it does not move with constant speed in a
perfect circular orbit around the earth! There were many
problem with the ‘perfect’ Greek heaven!
Great Greek Astronomer author of ‘Almagest’, Ptolemy, came
up with a ‘clever’ idea of epicycle. Though it explained back
and fore motion of planets, his geocentric model motion of
planets was ‘quite complicated’.
So for time, till Copernicus
pays
attention
to
this
deceptive planet, Venus kept
a
secrete,
well
hidden.
Copernicus did not like
Geocentric model of Ptolemy.
He suggested that if we assume that these planet goes around
the Sun, model of the universe becomes more elegant, almost
without ‘messy’ epicycles. This heliocentric model have a few
unique testable predictions…
… and one of prediction was that, if Venus goes around the
Sun it should show phases like Moon…
…We have to wait till
Galileo spies Venus
with his telescope. He
observed its phase and
confirmed Heliocentric
model of Copernicus.
For confirming that the planets goes round the Sun, along
with Galileo credit should go to Venus too!
But keep with its reputation of being deceptive, even with
the most powerful telescope Venus showed almost a
featureless disk.
It appeared that planet is covered by clouds!
Visual
Science fiction
Science fiction writers took fancy and speculated planet full
of life.
However what was found below the veil of clouds was world
stranger than imagined in mythologies and science fictions
Next to each other Earth and Venus will look like sisters
Like most siblings there are a hell lot of differences
between ‘planetary sisters’!
12742 ± 1.0 km[
12103.6 ± 1.0 km[
Both the Earth and Venus are of almost same size
4.868 5×1024 kg
5.9736×1024 kg
Though Earth and is bit more massive than the Venus
Rotational period (earth days): 243.0187ç
North
Rotation wise Venus is oddball of a planet.
All the planet in solar system rotates west to east, Venus
dose it from east to west and very very slowly! Probably it
was knocked down by an huge impact when solar system
was forming as a result its north pole is upside down.
176.30 243 days
224.7 days
If you happens to live on the Venus a day wont pass before
you are a year old!
108.2 million km
150 million
km
3.3940
176.30 243 days
23.50 1 days
Orbits of the Earth and Venus
Solid core
Core
Liquid core
Mental
Mental
Crust
Crust
Venus
Earth
Internal structure of both may not much different, however
unlike earth Venus don’t have a planetary magnetic field
and probably ‘plate tectonics’ might be missing too
In 1962 orbiter Mariner 2 was first successful mission, using
infrared and microwave radiometry it revealed that while cloud
top are cool but at the Venusian surface temperature reaches
4250 C
Venus Atmosphere profile
Atmospheric Composition
Temperature: 4600 C
Pressure: 93 Bar/ 100X Earth
~96.5% carbon dioxide
~3.5% nitrogen
0.015% sulfur dioxide
0.007% argon
0.002% water vapor
0.001 7% carbon monoxide
0.001 2% helium
0.000 7% neon
trace carbonyl sulfide
trace hydrogen chloride
trace hydrogen fluoride
Such a high temperature is caused by 96.5%carbon dioxide in
atmosphere of Venus. CO2 is known to be green house gas,
Venus appears to be victim of runaway greenhouse effect.
It rains on Venus, it rains sulfuric acid! However surface
remains dry because acid vaporizes before it could reach
ground. What a relief!!
Venus got hardly any water. Unlike Earth’s magnetosphere
Venus does not have magnetic shield , as a result solar winds
could reach its atmosphere unhampered. Solar winds can
Break down water in Hydrogen and Oxygen, and Hydrogen got
lost to space and Oxygen combined with sulfur formed Sulfur
dioxide.
The Pioneer Venus Orbiter was inserted into an orbit around Venus
in 1978, and remained there for over thirteen years studying the
atmosphere and mapping the surface with radar.
So that is what we have got is planet named after goddess of beauty
and love but in realty it is ‘incarnation of hell’! But any way it is a
reminder to us what might happen to Earth if we don’t stop global
warming caused by CO2 emission.
Russian mission Venera 13 was successful in sending these
images from the surface of this veritable hell of a planet.
Launched in 1989 Magellan probe mapped the surface of
Venus using Radar and measured planetary gravity
Numbers and state of preservation of impact features gives
estimate of most surface to be about 300 to 600 millions years
old.
Maat Mons
Magellan probe revealed a quite a strange land hidden by
clouds. This and following landscapes are generated by
computer using Magellan probes data.
Gula Mons
Keeping in with tradition, planet named after a goddess have its
feature named after goddesses and female scientist and
astronauts taken from many nations.
In the region of Ishtar Terra there is feature named after Indian
goddess ‘Lakshmi’. Only feature on Venus is named after a
male is Maxwell montes is highest mountain.
Volcanic doms
80% of Venusian surface consist of volcanic planes.
Launched in November 2005, ’Venus Express, is providing
a better understanding of the atmospheric dynamics.
You may not wants to have vacation on Venus. But some day
in the future humans or robotic astronaut may pay visit to this
‘hellish’ world. We should know why Venus is like it is. Did
some kind of life evolved on Venus too? Does it still survive
somewhere in some hidden habitable niche somewhere on it?
It might be sensible to send robotic rover to Venus, as its
devised by NASA.
You may not wants to have vacation on Venus. But some day
in the future we may pay visit to this hell of a planet. We should
know why it is like this. Did life evolved on Venus too. Does it
still survive somewhere in some hidden habitable niche
somewhere on it. Answer are important. Some time in far future
Life on the Earth might have to face similar conditions