|1|| || |
SOLAR SYSTEM: Comprising of the Sun, 8 Planets and Moons.
- Distances in the solar system are measured in Astronomical Units (AU)- which is simply the 'average distance between the Earth and the Sun'. 1 AU is approximatrly 150,000,000 (15 crore) km.
- Size: Most distant planet from the Sun is 'Neptune', which is at a distance of about 30 AU (450 crore km) from the Sun.
- Age: Surprisingly, our solar system was also formed around 4.5 billion (450 crore) years ago.
- The main star of our Solar system is the 'Sun' and 8 main planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
- Pluto was reclassified as a small planet in year 2006 as it's size is less than half the width of the USA.
- Five dwarf planets: Pluto, Cerus, Haumea, Makemake, Eris.
- Scientists estimate the age of the Universe to be about 14 billion (1400 crore) years ago.
- Solar System is located in the Milky Way galaxy with containing about 200 billion (20,000 crore) stars.
- Other galaxies exist outside 'Milky Way' galaxy and all galaxies are collectively called the 'Universe'.
|2|| || |
SUN: The star at the centre of our solar system.
- Size: Approximately 100 times bigger than earth. The diameter of the sun is about 14,00,000 km.
- Sun's energy output is about 400 billion (40,000 crore) MW (megawatt) and earth receives about 100 MW (10,000 crore MW) energy from Sun.
- It is almost perfectly circular in shape and accounts for about 99.8% of the total mass of our solar system.
- Surface Temperature: About 6000°C (11,000°F).
- Light travels from Sun to Earth in about 8 minutes 19 seconds. Sun is about 15 crore Km (93 million miles) away from earth.
- Sun is white, but it appears yellow due to the scattering of light in our atmosphere. 74% of sun's mass is hydrogen, 25% helium, 1% oxygen.
- Even Sun rotates around its axis and its rotation period at the equator is about 25 days.
- Sunlight at the top of Earth's atmosphere is composed of 50% infrared light, 40% visible light, and 10% ultraviolet light.
- A solar eclipse occurs when the Moon is between the Sun and the Earth.
|3|| || |
STARS: 400 billion(40,000 crore) stars in 1 galaxy(our Milky Way galaxy) alone.
- With as many as 500 billion (50,000 crore) galaxies in the universe, it is impossible to count how many stars are there in the universe.
- The nearest star to earth, apart from the Sun, is Proxima Centauri, which is about 40 trillion kilometres or 4.2 light-years away.
- If you ride a spacecraft, it will take about 40,000 to 50,000 years to reach 'Proxima Centauri'.
- When we look up at stars, we see light that left the star a long time ago. The light from Proxima Centauri takes about 4 years to get here. So if you are looking at it now, you are actually seeing how it was 4 years ago!
- Stars do not twinkle. The twinkling effect is merely the deflecting light from the star passing through the earth’s atmosphere before it reaches our eyes.
- A star shines as it releases energy- due to thermonuclear fusion of hydrogen into helium in its core. This energy traverses the star's interior and then radiates into outer space.
- Most stars are between 1 billion to 13 billion years old. Some stars may even be close to 13.8 billion years old- which is also the observed age of the universe.
- Sun is also a star but it appears so bright because it is the closest star to earth. Some of the other stars are 100 times more bigger than our Sun.
- Many stars seem 'single' stars but most of those stars are not single. They are actually two star systems. They are so far away and so they just appear as 1 star.
|4|| || |
MOON: Earth's only natural satellite and 5th largest moon in the solar system.
- Size: Diameter of moon is 3475 km (2160 miles)- about 27% or 1/4th of Earth's diameter.
- Orbit around the Earth: It takes about 27 days to complete an orbit around the Earth.
- Distance from Earth: About 384,400 km (238,855 km).
- Surface Temperature: -173°C (-279°F) to 115°C (239°F)
- Day Duration: Length of a day on Moon is 29.5 Earth days.
- On July 20, 1969, the first person to set foot on the Moon was Neil Armstrong of USA.
- A person would weigh much less on the Moon, just about one sixth (17%) of the weight on earth due to Moon's much weaker gravity than Earth. This is why the lunar astronauts could leap about 6 times higher on the moon.
- The Moon has no atmosphere- which is why the surface of the Moon is unprotected from meteorites, solar winds and has huge temperature variations. For the same reason, no sound can be heard on the Moon.
- Scientists believe that Moon was formed after a Mars-sized object crashed into earth about 4.5 billion years ago. A solar eclipse occurs when the Moon is between the Sun and the Earth. A lunar eclipse occurs when the Earth is between the Sun and the Moon.
|5|| || |
PLANET 1 MERCURY: 1st planet from the Sun and smallest of the 8 planets.
- Size: Smaller than earth- approximately 38% of earth's size.
- Orbit around the Sun: It takes about 88 earth days to complete an orbit around the Sun.
- Distance from Sun: 0.4 AU- which is about 60,000,000 (6 crore km).
- Moons: Mercury has no moons or satellites of its own.
- Surface Temperature: -175°C (−280°F) to 425°C (800°F). It has no atmosphere (wind/weather) to retain heat. Hence, it experiences the most extreme temperature variation with night temperature falling to about −175°C (−280°F).
- Day Duration: A single day on Mercury lasts about 58 Earth days.
- In 2012, NASA confirmed receiving images in which craters at the north pole contained water ice.
- The Romans named this planet after the swift-footed Roman messenger god 'Mercury'. If you were to stand on Mercury, the Sun would appear two and a half times bigger than it appears on Earth.
- Of the 8 planets, it is the smallest and closest to Sun. Its rotation period at the equator is about 88 days. Hence a year on Mercury is just 88 days long.
|6|| || |
PLANET 2 VENUS: 2nd planet from the Sun and the 2nd brightest object in the night sky after our Moon.
- Size: Very similar to size of earth. Diameter of Venus is only 650 km less than the Earth's diameter.
- Orbit around the Sun: It takes about 225 earth days to complete an orbit around the Sun.
- Distance from Sun: 0.7 AU- which is about 105,000,000 (10.5 crore km).
- Moons: Like Mercury, Venus also has no moons or satellites of its own.
- Surface Temperature: About 460°C (860 °F)- which makes it the hottest planet in our solar system. Even hotter than Mercury.
- Day Duration: A single day on Venus last about 243 Earth days- the slowest rotation period of any planet.
- Very little light reaches the surface as the clouds are very thick. The little light that does reach the surface is converted to heat and cannot escape the atmosphere making Venus the hottest planet in our solar system.
- The planet was named 'Venus' after the Roman goddess of love and beauty. Venus is the only planet in the Solar System to turn clockwise. All other planets turn anti-clockwise.
- On Venus, a person would immediately be crushed by Venus' amazingly strong atmospheric pressure.
|7|| || |
PLANET 3 EARTH: 3rd planet from the Sun, 5th largest of 8 planets.
- Size: Diameter of Earth is about 12,750 km (7920 miles). Total area: 51 crore (510 million) sq km.
- Orbit around the Sun: It takes about 365 earth days to complete an orbit around the Sun.
- Distance from Sun: 1 AU- which is about 150,000,000 (15 crore km).
- Moons: Earth has 1 moon (See details below).
- Surface Temperature: -89°C (-128°F) to 55°C (131°F).
- Day Duration: 24 hours (1 day).
- About 29% of earth's surface is land comprising of 14.9 crore (149 million) sq km. 71% of earth's surface is water and 97% of water on earth is salted. 90% of all volcanic activity occurs in the ocean.
- Earth is not exactly round. It is slightly flattened on the top and bottom poles. Also, its core temperature is about 6,000°C(11,000°F) which is just as hot as the sun’s surface.
- Due to the constant movement of the tectonic plates, continents move about 2 cm every year. For list of countries, capitals and currencies: Click here
|8|| || |
PLANET 4 MARS: 4th planet from the Sun, 2nd smallest of 8 planets.
- Size: Diameter of about half the Earth, measuring only 6,800 km (4225 miles).
- Orbit around the Sun: It takes about 687 days to complete an orbit around the Sun, twice as long as Earth’s 365-day journey.
- Distance from Sun: 1.5 AU- which is about 225,000,000 (22.5 crore km).
- Moons: Mars has 2 known moons: Phobos and Deimos.
- Surface Temperature: -87°C (-125°F) to -5°C (23°F).
- Day Duration: 24.6 hours- One Mars day is 1 Earth day and 37 Minutes.
- Mars is often called the ‘Red Planet’ due to the iron oxide prevalent on its surface, which gives it a reddish look. It is a dry dusty desert and has huge deposits of water underneath the surface across the planet in the form of ice.
- Mars has the 2nd highest known mountain within the Solar System - the Olympus Mons - with a height of about 22 km (14 miles) and stands almost 3 times as tall as Mount Everest’s height above sea level.
- One cannot survive on the surface of Mars without a spacesuit and would die almost immediately due to the freezing cold temperatures and the thin atmosphere. The air pressure is only 1% the pressure on Earth.
|9|| || |
PLANET 5 JUPITER: 5th planet from the Sun and largest of the 8 planets.
- Size: Diameter of 143,000 km (88,850 miles) which is 11 times greater than that of Earth. Over 1,300 earths could fit inside it.
- Orbit around the Sun: It takes about 4330 days (11.8 earth years) to complete an orbit around the Sun.
- Distance from Sun: 5.2 AU- which is about 780,000,000 (78 crore km).
- Moons: 67 moons. Almost all of them are less than 10 kilometers in diameter.
- Surface Temperature: -150°C (-234°F).
- Day Duration: Length of a day on Jupiter is 9 hours and 55 minutes.
- Jupiter is the fastest rotating planet in our solar system. A day on earth lasts about 24 hours, while on Jupiter, a day passes in less than 10 hours.
- It has a very strong magnetic field and the strongest gravity of all the planets. You would weigh about 3 times as much as you would on Earth.
- Jupiter has an interesting 'Great Red Spot'- a huge storm of swirling gas that is larger than earth and has lasted for more than 300 years.
|10|| || |
PLANET 6 SATURN: 6th planet from the Sun and 2nd largest of the 8 planets.
- Size: Diameter of 120,500 km (74,875 miles), nearly 10 times wider than Earth. Over 750 earths could fit inside it.
- Orbit around the Sun: It takes about 10,800 days (29.5 earth years) to complete an orbit around the Sun.
- Distance from Sun: 6 AU- which is about 900,000,000 (90 crore km).
- Moons: 62 moons.
- Surface Temperature: -139 °C (-218°F). Saturn has no real surface as it is made up of gases that gradually merge into a hot ocean of liquid hydrogen and helium.
- Day Duration: Length of a day on Saturn is 10 hours and 32 minutes.
- Saturn's Titan is the 2nd largest moon(bigger than Mercury) in the solar system but most of its other 61 moons are just a few km in size and very small. Only Jupiter’s moon Ganymede is larger.
- Saturn's rings are only a few hundred feet thick (less than half the length of a football field). It is not the only planet with rings. Jupiter, Uranus, and Neptune also have very faint rings. Saturn rings are made up of ice but the 3 rings of Jupiter are made up of dust.
- Saturn is one of 5 planets that can be seen with the naked eye on a clear night. Other 4 are Mercury, Venus, Mars and Jupiter. Saturn often has a yellowish color that does not twinkle in the night sky.
|11|| || |
PLANET 7 URANUS: 7th planet from the Sun and 3rd largest of the 8 planets.
- Size: Diameter of 51,100 km (31,750 miles)- nearly 4 times wider than Earth.
- Orbit around the Sun: It takes about 84 earth years to complete an orbit around the Sun.
- Distance from Sun: 19.2 AU- which is about 2,880,000,000 (288 crore km).
- Moons: 27 moons.
- Surface Temperature: -197°C (-322°F).
- Day Duration: Length of a day on Uranus is about 17 hours.
- Lowest atmospheric temperature recorded is −224°C (-371°F) making Uranus the coldest planet in the solar system. It has no solid surface and is one of the gas giant planets like are Jupiter, Saturn and Neptune.
- This was the '1st planet' discovered with the help of a telescope in 1781.
- Uranus has two sets of rings, nine inner rings and two outer rings.
|12|| || |
PLANET 8 NEPTUNE: 8th and farthest planet from the Sun.
- Size: Diameter of 49,500 km (30,750 miles)- nearly 4 times wider than Earth.
- Orbit around the Sun: It takes about 165 years to complete an orbit around the Sun.
- Distance from Sun: 30 AU- which is about 4,500,000,000 (450 crore km).
- Moons: 14 moons.
- Surface Temperature: -200°C (-328°F).
- Day Duration: Length of a day on Neptune is about 16 hours.
- Neptune has the strongest winds in the solar system with hurricane speed like winds of upto 2,400 km/hour (1500 miles/hour).
- The interior of Neptune, like Uranus, is primarily composed of ice and rock.
- Neptune is the smallest of the gaseous planets in the Solar System: Jupiter, Saturn and Uranus. But, it is actually more dense than Uranus.