2. List of the Topics
1. Celestial Objects
2. Astronomy
3. Astronaut's
4. Astronomy in Ancient India
5. Sun
6. Moon
7. Planets
8. Mangalyaan
9. Artificial Satellites
10. Asteroids
11. Why Pluto is dropped as a planet?
3. Celestial Objects
A Celestial Object is the natural object outside of the Earth’s Atmosphere.
Examples : Stars, Planets, Sun, Natural Satellites, Asteroids, Comets etc.
4. Astronomy
Astronomy (from the Greek Astron (ἄστρον) meaning "star" and nomos (nόμος) meaning "law")
is the scientific study of celestial bodies. The objects studied include stars, galaxies, planets,
moons, asteroids, comets and nebulae.
A telescope is an instrument that is
used to view celestial objects.
5. Astronaut's
An astronaut is someone who travels in space.
Yuri Gagarin was a Soviet Air Forces pilot who became the
first Astronaut his capsule Vostok 1 completed one orbit of
Earth on 12 April 1961.
The first Indian to travel to space is Rakesh Sharma. He flew
aboard the Soviet rocket Soyuz T-11 launched in April 1984.
Valentina Vladimirovna Tereshkova is the first and youngest
woman to have flown in space with a solo mission on the
Vostok 6 on 16 June 1963.
Kalpana Chawla is the first woman of Indian descent to go to space.
She first flew on Space Shuttle Columbia in 1997 as a mission specialist and primary robotic arm
operator.
6. Astronomy in Ancient India
Aryabhatta is said to have been born in 476 A.D. at a town called Ashmaka in today's Indian
state of Kerala.
His book, The Aryabhatiya, published in 498 AD described numerical and geometric rules for
eclipse calculations.
He gives the radius of the planetary orbits in terms of the
radius of the Earth/Sun orbit as essentially their periods
of rotation around the Sun.
He was also the earliest to discover that the orbits of
the planets around the Sun are ellipses.
7. SUN
The Sun is the heart of our solar system, it is a yellow dwarf star with a hot ball of glowing
gases.
The Sun is the source of almost all energy on the earth. It continuously emitting huge amount
of heat and light.
It is approx. 4600 million years old.
The Sun has eight known planets. This includes four terrestrial planets (Mercury, Venus, Earth,
and Mars), two gas giants (Jupiter and Saturn),
and two ice giants (Uranus and Neptune).
The Solar System also has at least five dwarf planets,
an asteroid belt, numerous comets, and a large number
of icy bodies which lie beyond the orbit of Neptune.
8. Moon
It is a natural satellite of earth.
It is a Non- Luminous body.
The first astronaut to step into the moon is Neil Armstrong.
It is a rocky desert.
Temperature in day time 100°c
Temperature at night 168 ° c
The moon’s surface is dusty and barren.
It also has a large number of steep and high mountains.
Some of these are as high as the highest mountains on
the earth.
9. Phases of Moon
The various shapes of the bright part of the moon as seen during a month are called phases of
moon.
The full moon is the phase when the Moon appears fully illuminated from Earth’s
perspective.
A Lunar eclipse occurs when Earth is
located between the Sun and the Moon.
The new moon is the phase that is
invisible to us here on Earth because
the moon is between the earth and the sun,
and its illuminated side is facing away
from us.
A solar eclipse occurs when the
moon moves in front of the sun.
10. Planets
The planets look like stars, but they don’t have their own light.
The simplest method of identifying planets from stars is that stars twinkle, whereas planets don’t.
Every planet has a definite path in which it revolves around the sun. This path is called as Orbit.
The time taken by a planet to complete one revolution is called its period of revolution.
This period of revolution increases as the distance of the planet increases from the sun.
11. Mercury
Mercury is the smallest and innermost planet in the Solar System.
Its orbit around the Sun takes 87.97 days, the shortest of all the planets in the Solar System.
It is so close to sun, it is very difficult to observe it. It has no natural satellites.
12. Venus
Venus is the second planet of the solar system. As the second-brightest natural object in
the night sky after the Moon,
Venus orbits the Sun every 224.7 Earth days.
It is earth’s nearest planetary neighbor.
13. Earth
Earth is the third planet from the Sun.
It is the only planet in the solar system on which life exist.
It has a naturally satellite called as Moon.
From space, the earth appears blue & green due to the reflection of light from water and
landmass on its surface.
Earth orbits around the Sun in 365days.
14. Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar
System after Mercury. It is often referred to as the 'Red Planet’
Its orbital period is 687 (Earth) days.
Mars have two natural satellites(moons) that is Phobos (panic/fear) and Deimos (terror/dread)
and one artificial satellite which was sent by our Indian space station ISRO called as
Mangalyaan.
15. Mangalyaan
ISRO(Indian space research organization) launched India’s first Mars orbiter Mission called as
Mangalyaan, on November 5th 2013, and successfully places into an orbit of mars on
September 24th 2014.
16. Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is one of the
brightest objects visible to the naked eye in the night sky.
It is so large that about 1300 earths can be placed inside this giant planet.
It completes an orbit every 11.86 years.
It has 4 natural satellites/moons names as Io, Europa, Ganymede, and Callisto—are among the
largest satellites in the Solar System.
The moons is discovered by scientists Galileo,
Hence it is called as Galileo moons.
17. Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System,
after Jupiter.
Saturn is over 95 times of earth. It takes 10,759 Earth days (or about 29 1⁄2 years) to finish one
revolution around the Sun.
It has a beautiful rings which are not visible to our naked eye. It can seen with the help of
telescope. These rings makes the planet a unique one in our solar system.
It also have 83 natural satellites/moons.
18. Uranus
Uranus is the seventh planet from the Sun.
Uranus orbits the Sun once every 84 years.
It has 27 known natural satellites.
19. Neptune
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
Neptune is 17 times the mass of Earth, slightly more massive than its near-twin Uranus.
It has 14 known moons around its axis.
20. Why Pluto is dropped as a planet?
In August 2006 the International Astronomical Union (IAU) downgraded the status of Pluto to that of “dwarf
planet.”
A “dwarf planet,” as defined by the IAU, is a celestial body in direct orbit of the Sun that is massive enough that
its shape is controlled by gravitational forces rather than mechanical forces (and is thus ellipsoid in shape), but has
not cleared its neighboring region of other objects.
So, the three criteria of the IAU for a full-sized planet are:
1. It is in orbit around the Sun.
2. It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape).
3. It has “cleared the neighborhood” around its orbit.
21. Asteroids
o There is a large gap between orbits of Mars and the Jupiter, this gap is occupied by a large
number of small objects that revolve around the sun, these are called Asteroids.
o It is visible through large telescopes only.
22. Artificial Satellites
Artificial satellites are man-made satellites. They are launched from the earth with the help of
rockets. They revolve around the earth much closer than earth’s natural satellite(moon).
Aryabhata was the first Indian satellite.
Artificially satellite are used for-
• Weather forecasting.
• Television and radio signals.
• Telecommunication.
• Remote sensing.
