Chapters :

Universe – 02


Mars The red planet is dusty, cold world with a thin atmosphere , It is said to be called “Red planet”. It is reddish in colour due to the presence of iron oxide on its surface.

  • Mars is the fourth planet from the Sun and the second-smallest planet of the Solar System.
  • Mars is the most widely searched planet for life, inspiring many works of fiction.
  • The first person to observe Mars with the use of a telescope was Galileo Galilei. He observed the Red Planet in 1610.
  • Mars is 227.9 million kilometers / 141.6 million miles away from the Sun.
  • Light from the Sun reaches Mars in about 13 minutes.
  • Mars is around two times smaller than Earth. It has a diameter of 6.779 km / 4.212 mi.
  • Mars is around 10 times less massive than Earth.
  • Mars is the outermost terrestrial planet, outside Earth’s orbit. It is 50% farther away from the Sun than Earth.
  • Mars has two known natural satellites, Phobos and Deimos.
  • Phobos is predicted to suffer a collision with Mars in the distant future.
  • The atmosphere on Mars is thin, mostly comprised of carbon dioxide, nitrogen, and argon gases.
  • The tallest volcano/mountain in the Solar System is located on Mars. It is named Olympus Mons and it seems to have a height of 21 km / 13 mi.
  • Mars also has the biggest canyon in the Solar System. It is named Valles Marines. It is 4.000 km / 2.500 mi long and reaches depths of 7 km / 4 mi deep. The Grand Canyon on Earth is only 446 km / 226 mi long, and only 1.6 km / 1 mi deep.
  • Mars doesn’t have a magnetic field however some areas are highly magnetized.
  • The average temperatures on Mars is -80 degrees Fahrenheit / -60 degrees Celsius.


The planet Jupiter is named after the supreme Roman god. To the ancient Greeks, he was known as Zeus, ruler of the Greek gods, and Mount Olympus.

It is the largest planet in the solar system. It is made primarily of gases and is therefore known as ‘Giant Gas planet’.

 Jupiter is a massive planet, twice the size of all other planets combined and has a centuries-old storm that is bigger than Earth

  • Jupiter is the fifth planet from the Sun and the biggest planet of our Solar System. Some consider it a failed star since it is made out of swirling gases and liquids such as 90% hydrogen, and 10% helium – very similar to the Sun.
  • Jupiter is the fourth brightest object in the sky and one of the five visible planets ( Mercury, Venus, Mars, Saturn ).
  • The envelope of gases – atmosphere – surrounding Jupiter is the largest planetary atmosphere in the Solar System. It makes up almost the entire planet. Basically, it doesn’t have a true surface with its atmosphere reaching altitudes of 5.000 km / 1.864 mi.
  • Through the observations of Jupiter, the discovery of the four Galilean moons ended the belief that everything revolved around the Earth.
  • Jupiter has a total of  67 confirmed moons. It is second only to Saturn when it comes to the total amount of satellites.
  • Jupiter also has 3 ring systems but much smaller than Saturn’s.
  • Though they can be seen only through ultraviolet, Jupiter’s auroras are the brightest in the Solar System.
  • Jupiter has a mean radius of 69.911 kilometers / 43.440 miles, a diameter at the equator of around 142.984 km / 88.846 mi, and a diameter at the poles of 133.708 km / 83.082 mi.
  • Jupiter’s mass is almost twice of all the Solar System’s planets combined. It is 318 times more massive than Earth.
  • Jupiter is on average about 5.2 AU away from the Sun. One AU is equivalent to 150 million km / 93 million mi.
  • Jupiter experiences 200 times more asteroid and comet impacts than Earth.
  • In a way, Jupiter is the Solar System’s vacuum cleaner, because of its powerful gravity which attracts many of the comets and asteroids to hit it rather than other planets.


The planet Saturn is named after the Roman god of agriculture. In Greek mythology, he is known as Cronus, the father of Zeus (Jupiter). Saturn is the root of the English word “Saturday.”

 It is the only planet in our solar system whose average density is less than water. Titan is Saturn’s largest moon and the second largest (after Ganymede of Jupiter) in the solar system. It is the only moon in the solar system with clouds and a dense, planet-like


  • Saturn is the sixth planet from the Sun with the largest planetary rings in the Solar System.
  • It is the second-largest planet in the Solar System after Jupiter.
  • Saturn has a radius of 58.232 kilometers / 36.183 miles and a diameter of 120.536 km / 74.897 mi.
  • The surface area of Saturn is 83 times greater than Earth.
  • Saturn is the King of the Moons, having a total of 82 confirmed moons. There are probably more out there.
  • The largest moon of Saturn is named Triton, and it is the second-largest moon in the Solar System after Jupiter’s moon Ganymede. Triron is much bigger than even the planet Mercury.
  • Periodic storms are present on Saturn and they are large enough to be seen from Earth. They are named White Spots.
  • Saturn doesn’t have a solid surface. It is enveloped by swirling gases and liquids the further down you go. 
  • It is possible that Saturn may have a core, it would be at least twice the size of Earth and it would be comprised out of metals like iron, and nickel.
  • The temperature on Saturn’s upper atmosphere is on average at around -175 degrees Celsius / -285 degrees Fahrenheit. This is quite cold for a gas giant at least. However, below its clouds, it gets considerably hotter.
  • Saturn has the lowest density of all the planets. It is lighter than water and if placed on it, the planet would float.
  • The low density of Saturn is attributed to its composition. The planet is largely made up of gases such as hydrogen and helium.
  • Saturn’s composition together with its atmosphere influences its color, giving it a brownish-yellow appearance.

B.B – Show the Below Content in Vertical tabular form 

Name of Planet                                   Image of Planet                         No of Satellites

Name Of The Planet:  Mercury   Venus   Earth Mars Jupiter Saturn Uranus Neptune

Number of Satellites:    0               0           1        2         67           53           27          13

The planets orbit around the sun in elliptical path , the point  close(Perihelion) to the sun and  far away (Aphelion) from the sun.


  Any celestial body orbiting around the sun, weighing for the self gravity and nearly be round in shape is called ‘Dwarf Planet’.

E.g.: Ceres, Pluto, Heumea, Makemake and Eris


The satellites move around a planet from West to East. 

They do not have own light,but reflect the light of the Sun. 

They haveno atmosphere and water.

The moon is the earth’s natural satellite. 

The moon moves around the earth in about 27 days. It takes exactly the same time to complete one spin. As a result, only one side of the moon is visible to us on the earth.


Asteroids are small rocky celestial bodies that revolve around the Sun, like other

Planets. These are found in between the planets Mars and Jupiter. This belt is known as ‘Asteroid belt’.

When an asteroid collides with the earth, then a huge crater is formed on the surface of the earth. For example: lonar lake in maharastra.


nlike the other small bodies in the solar system, comets have been known since antiquity. There are Chinese records of Comet Halley going back to at least 240 BC. The famous Bayeux Tapestry, which commemorates the Norman Conquest of England in 1066, depicts an apparition of Comet Halley.

By far the most famous comet is Comet Halley but SL 9 was a “big hit” for a week in the summer of 1994.

Meteor shower sometimes occur when the Earth passes thru the orbit of a comet. Some occur with great regularity: the Perseid meteor shower occurs every year between August 9 and 13 when the Earth passes thru the orbit of Comet Swift-Tuttle. Comet Halley is the source of the Orionid shower in October.

Comet Comets are snowballs made up of frozen gas, rock, and dust that orbit the Sun. As they get closer to the Sun, they heat up and leave a trail of glowing dust and gases

Comet is also the heavenly body located on the outermost part of the solar system. They are made up of small ice particles and meteoric fragments. As the comet approaches the sun, it develops a long, glowing tail.

Comets are sometimes called dirty snowballs or “icy mudballs”. They are a mixture of ices (both water and frozen gases) and dust that for some reason didn’t get incorporated into planets when the solar system was formed. This makes them very interesting as samples of the early history of the solar system.

When they are near the Sun and active, comets have several distinct parts:

  • nucleus: relatively solid and stable, mostly ice and gas with a small amount of dust and other solids;
  • coma: dense cloud of water, carbon dioxide and other neutral gases sublimed from the nucleus;
  • hydrogen cloud: huge (millions of km in diameter) but very sparse envelope of neutral hydrogen;
  • dust tail: up to 10 million km long composed of smoke-sized dust particles driven off the nucleus by escaping gases; this is the most prominent part of a comet to the unaided eye;
  • ion tail: as much as several hundred million km long composed of plasma and laced with rays and streamers caused by interactions with the solar wind.


Meteoroids are lumps of rock or iron that orbit the sun, just as planets, asteroids, and comets do. 

Meteoroids, especially the tiny particles called micrometeoroids, are extremely common throughout the solar system. 

They orbit the sun among the rocky inner planets, as well as the gas giants that make up the outer planets. 

A meteoroid, comet, or asteroid enters Earth’s atmosphere at a speed typically in excess of 20 km/s (72,000 km/h; 45,000 mph), aerodynamic heating of that object produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called a meteor or “shooting star”. A series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower. A meteorite is the remains of a meteoroid that has survived the ablation of its surface material during its passage through the atmosphere as a meteor and has impacted the ground.

An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth’s atmosphere each day, which results in an estimated 15,000 tonnes of that material entering the atmosphere each year


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