الأربعاء، 24 سبتمبر 2014

The Earth’s Twin

The Earth’s Twin
Venus is the second planet from the Sun. It is also Earth’s closest
neighbour and its size, composition, gravity and distance from
the Sun are similar to the Earth’s. Venus is so similar to Earth,
that it is often considered to be its twin. However, in reality,
Venus is very different.
Q Why is Venus hotter than Mercury?
A Venus has a thick atmosphere, much
thicker than the Earth’s. The atmosphere is
mainly carbon dioxide. This greenhouse gas
traps large amounts of heat within the planet.
That is why Venus is hotter than Mercury, Q Are there volcanoes on Venus?
A There are more volcanoes on Venus
than there are on Earth. About 80 per cent
of the planet’s surface is made up of smooth
volcanic plains, and there are two major
mountain ranges with volcanoes that may
be active. The peak of Maxwell Montes,
the highest mountain on Venus, lies 11
kilometres (7 miles) above the surface
of the planet. Mount Everest rises only
about 9 kilometres (6 miles) above sea level.
Mapping Venus
Scientists have sent
a number of space
missions to Venus to
find out more about
its size, atmosphere,
interior and surface,
especially its volcanoes.
Volcano on Venus
There is far more volcanic
activity inside Venus than
inside Earth; so, Venus has
many more volcanoes.
Spinning backwards
though Mercury is closer to the Sun.
Q Why is a day longer than a year
on Venus?
A Venus goes around the Sun at a very
high speed. It takes only about 225 days to
complete one orbit. However, it spins much
more slowly on its axis, taking about 243
days to complete a rotation. Therefore,
days on Venus are longer than years.
Earth
rotation
Sun
Venus
All the planets rotate from west to east
on their axes, apart from Venus, which
spins in the opposite direction. On the
surface of Venus, the Sun appears to rise
in the west and set in the east. The planet
might have been hit by a huge space
rock, reversing the direction of its spin.
Try these too…
The Sun (10–11), The
King of Planets (17), The
Moon (20–21), Comets
and Asteroids (22–23),
Earth’s Atmosphere
(26–27), The Poles – The
Arctic and Antarctica
(122–123

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