Category The Universe, Exploring the Universe, Solar System, The Moon, Space, Space Travel

MARS

Although Mars is much smaller than Earth, the two planets have a number of similarities. The Martian day is only a little longer than ours and its angle of tilt means that Mars has four seasons, just as we do on Earth. Daytime temperatures at the equator in midsummer can sometimes reach 25°C. Thin clouds of water vapour or early morning surface frosts can also sometimes be seen. Like Earth, Mars has volcanoes, mountains, dried-up river beds, canyons, deserts and polar icecaps.

For these reasons, Mars is thought to be the only other planet where life may once have existed. However, analysis of the Martian soil by space probes Viking 1 and 2, which touched down on the planet in 1976, and Pathfinder in 1997, failed to find any sign of past or present life.

Mars is a barren planet. Its reddish colour comes from iron oxide dust (similar to rust). From time to time, large dark regions appear on the surface. These are areas of bare rock, exposed when storms remove the dusty covering. The Martian landscape features some dramatic landforms. The Solar System’s highest mountains and its deepest canyon, Valles Marineris, are found on Mars.

Mars has quite a low density and a very weak magnetic field. This suggests that it has only a relatively small ball of iron at its core.

 A number of valleys and channels have been carved into the Martian plains. From the evidence of sediments – muds and silts deposited by water – it seems likely that there were once rivers, lakes and even seas on Mars. The only water left on the surface today is frozen in the polar icecaps. The rest may have been lost to space due to Mar’s weak gravity, or hidden from view as a deep-frozen layer beneath the surface.

Picture Credit : Google

 

MOON

The moon is neither a star nor a planet. It is a ball of rock that travels around Earth, taking about 27 days to complete the circle. It is the brightest object in the night sky, although the light it “shines” is reflected from the Sun.

The Moon may have formed when a large object or planetesimal collided with the newly-formed Earth more than four billion years ago. The impact “splashed” into space vast amounts of debris that later came together to form the Moon.

            A completely barren world, the Moon’s surface consists of cratered highlands and wide plains. The Moon’s internal structure is similar to Earth’s; its crust is thicker and not divided into tectonic plates.

            With neither air nor liquid water, it is impossible for plants or animals to live on the Moon. The barren lunar landscape is pitted with craters, blasted out by meteorites crashing to its surface. Scattered debris has left streaks radiating from some craters. The Moon also has wide, smooth lava plains. Early astronomers thought these were seas. They are still called by the Latin name for sea, mare.

PHASES OF THE MOON

The shape of the Moon appears to change from one night to the next. This happens because, as it travels round Earth, it spins only once, so the same face remains pointed towards us at all times. It is our view of the sunlit part that changes. When the face pointed towards us is turned away from the Sun, we cannot see the Moon at all: a New Moon (1).When it is turned towards the Sun, we see a complete disc: a Full Moon (5). In between, it passes through crescent (2), quarter (3) and gibbous (4) phases, and back again (6-8).

Picture Credit : Google

SATURN

All four gas giants have rings, but Saturn’s, visible from Earth through even a small telescope, are broad, bright and magnificent. As detailed photographs taken by Voyager 2 show, the rings are made up of billions of blocks of ice and rock, ranging in size from boulders as large as houses down to tiny fragments the size of snowflakes. They are only a few tens of metres thick. Some astronomers think that the rings are the fragmented remains of a moon that was smashed apart by a passing comet.

Three rings can be made out from Earth. The outer ring (A ring) is separated from the other two lying inside it (B and C) by a gap called the Cassini Division. Voyager 2 spotted fainter rings beyond A ring. It also revealed that each ring was, itself, divided into thousands of ringlets.

Saturn has a large family of moons, many of which are small, irregularly shaped bodies with some even sharing the same orbits.

Swirling clouds and storms can sometimes be seen as ripples on Saturn’s globe. Saturn rotates very quickly, producing a distinct bulge at its equator. It is the least dense of the planets: if a large enough bathtub could be found, Saturn would float in the water!

Picture Credit : Google

JUPITER

Jupiter is the largest planet in the Solar System. Large enough to contain more than 1300 Earths inside it, Jupiter is more massive than all the other planets combined. Along with Saturn, Uranus and Neptune, Jupiter is known as a “gas giant”, because it is mostly made of gas with no solid surface at all.

The colourful patterns of red, brown, yellow and white on Jupiter’s surface are produced by the chemicals sulphur and phosphorus in the swirling atmosphere. Jupiter’s extremely quick rotation is probably responsible both for separating the clouds into different colour “zones” (the lighter bands) and “belts” (the darker bands), and for the continual storms. The Great Red Spot, its most famous feature, is such a storm. The quick rotation also causes Jupiter to bulge at its equator, so that it measures 7500 kilometres less from pole to pole.

Jupiter has a system of rings consisting of dark grains of dust. The four largest of its moons are bigger than the planet Pluto. The beautiful, ever-changing patterns on Jupiter’s globe are violent winds.

Picture Credit : Google

VENUS

About the same size as Earth, Venus is shrouded in thick, unbroken clouds made of droplets of deadly sulphuric acid. Because its cloud cover reflects the light of the Sun from its surface, Venus is a very bright object in the night sky.

Some 25 kilometres thick, the clouds prevent most sunlight from reaching the surface. But another kind of radiation from the Sun, called infrared, does get though and Venus’s dense atmosphere stops it from escaping. The result is a constant surface temperature hotter than the melting point of lead and the hottest in the Solar System. If any space explorer landed on Venus, he or she would be simultaneously incinerated, suffocated by the unbreathable carbon dioxide air, dissolved by acid and crushed by air pressure about 90 times that on Earth.

Venus spins slowly on its axis, actually taking longer to complete one rotation than to orbit the Sun. Relative to all the other planets except Pluto, it spins backwards.

            Venus is covered by thick clouds. They race round in the planet in just four days. The interior of Venus is similar to that of Earth, although its metallic core is much larger than Earth’s.

            Beneath the clouds, Venus’s barren surface features tens of thousands of volcanoes (some possibly still active) surrounded by vast lava plains. Lava flows have cut channels in the ground that look as if they may have been carved by rivers. Odd, dome-shaped volcanoes, or “pancakes”, as they have been described, have formed where lava has oozed to the surface, and then cooled as it spread out in all directions.

Picture Credit : Google