Page 190 - Science Class 08

Planet Average Diameter Mass in Time to Time of Known
distance at equator rela on to orbit the rota on on number of
from the sun (km) the earth sun axis moons
(million km) (Earth = 41)

Mercury 58 4880 0.06 88 days 58 days 0

Venus 108 12100 0.82 225 days 243 days 0

Earth 150 12800 1 365 days 24 hours 1

Mars 228 6800 0.11 687 days 24 h 37 m 2

Jupiter 778 142800 318 12 years 9 h 55 m 28

Saturn 1427 120000 95 29.5 years 10 h 39 m 30

Uranus 2871 50800 14.5 84 years 10 h 14 m 21

Neptune 4497 48500 17 165 years 16 h 7 m 8

Pluto 5913 3000 0.002 248.5 years 6 d 9 h 1

ARTIFICIAL SATELLITES Two Important Types of Satellite Orbits
Man has made several satellites that orbit the On the basis of the orbits of the satellites they
earth. These ar ficial satellites are large can be categorised into two groups:
laboratories that carry out many experiments
v Geosta onary Satellites
in the space. The first ar ficial satellite,
v Sun-Synchronous Orbit Satellites
Sputnik–I was launched by the USSR in 1957.
India launched several satellites like Arya– v Geosta onary Satellites : A geosta onary
bha a (1975) followed by Bhaskara – I (1979), satellite is a satellite that remains fixed
Rohini (1980), Apple (1981) Insat 1991, Gsat with respect to a par cular point on the
(2001), Chandrayaan-1 (2008), Chandrayaan-2 earth. The me period of their revolu on
(2019) etc. around the earth is the same as the me
period of rota on of the earth about its
own axis, i.e., nearly 24 hours.

Ar ficial Satellites
Ar ficial satellites are used in telecomm-
unica on, television and radio broadcas ng,
weather forecas ng and studying the universe. Geosta onary Satellite

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