Universe Flashcards
Who proposed the heliocentric model (heltos Sun), with Sun at the centre of the solar system.
Nicolaus Copernicus
Nearly all of the matter in the universe that we understand is made of ___________, the simplest elements, created in the Big Bang
hydrogen and helium
Which galaxy is our closest neighboring galaxy
Andromeda
Our solar system is _______ away from the centre of our galaxy.
25,000 light years
Just as the Earth goes around the Sun, the Sun goes around the centre of the galaxy and it takes ______ years to do that.
250 million
_______ are the fundamental building blocks of galaxies.
Stars
The brightness of a star depends on their ___________ from the Earth
intensity and the distance
Stars also appear to be in different colours depending on their ______
temperature
Hot stars are __________ whereas cooler stars are _________ in colour.
white or blue,
orange or red
A group of stars forms an imaginary outline or meaningful pattern on the space. They represent an animal, mythological person or creature, a god, or an object. This group of stars is called
constellations
People in different cultures and countries adopted their own sets of constellation outlines. There are ______ formally accepted constellations. Aries, Gemini, Leo, Orion, Scorpius and Cassiopeia are some of the constellations.
88
Sun has hydrogen and helium of _____ ratio
3:1
The period of rotation of earth
23 hrs 56 mins
Mercury
58.65 days
Venus
243 days
Earth
23.93 hrs
Mars
24.62 hrs
Jupiter
9.92 hrs
Saturn
10.23 hrs
Uranus
17 hours
Neptune
18 hours
Farther from the Sun is the outer solar system, where the planets are much more spread out. Thus the distance between Saturn and Uranus is much ___________ than the distance between the Earth and the Mars.
greater (about 20 times)
The four planets grouped together in the inner solar system are Mercury, Venus, Earth and Mars They are called inner planets. They have a surface of solid rock crust and so are called _________,
terrestrial or rocky planets
The four large planets Jupiter, Saturn, Uranus and Neptune spread out in the outer solar system and slowly orbit the Sun are called outer planets. They are made of hydrogen, helium and other gases in huge amounts and have very dense atmosphere. They are known as __________ The four outer planets Jupiter, Saturn, Uranus and Neptune have rings whereas the four inner planets do not have any rings
gas giants and are called gaseous planets)
Mercury can be easily observed thorough ________ than naked eye
telescope
It always appears in the eastern horizon or western horizon of the sky
After our moon, it is the brightest heavenly body in our night sky. This planet spins in the opposite direction to all other planets. So, unlike Earth, the Sun rises in the west and sets in the east here.
Venus
Venus can be seen clearly through naked eye. It always appears in the horizon of eastern or western sky.
Mars has two small natural satellites
(Deimos and Phobos).
Jupiter is called as Giant planet. It is the largest of all planets (about _____ times larger and ______ times heavier than Earth).
11
318
. It has ____ rings and _____ moons
3 and 65(as 2023 Jupiter has 95 moon )
Its moon _____ is the largest moon of our solar system.
Ganymede
______ appears yellowish in colour. It is the second biggest and a giant gas planet in the outer solar system.
Saturn
At least ______ moons are present at saturn
60
_____ is the only moon in the solar system with clouds.
Titan
Largest moon in saturn
______ Having least density of all (30 times less than Earth), this planet is so light.
Saturn
Uranus has the longest summers and winters each lasting ____.
42 years
Neptune has _____ moons . ____ being the largest.
13
Triton
_______ is the only moon in the solar system that moves in the opposite direction to the direction in which its planet spins.
Triton
The biggest asteroid is ______&________ km across.
Ceres - 946
________ are lumps of dust and ice that revolve around the Sun in highly elliptical orbits. Their period of revolution is very long
Comets
One such comet is ________ Comet, which appears after nearly every 76 years. It was last seen in 1986. It will next be seen in 2062.
Halley’s
They are small pieces of rocks scattered throughout the solar system
Most of them are burnt up by the heat generated due to friction in the Earth’s atmosphere. They are called
meteors
Some of the bigger meteors may not be burnt completely and they fall on the surface of Earth These are called .
meteorites
A body moving in an orbit around a planet is called .
satellite
The Sun travelling at a speed of 250 km per second (9 lakh km/h) takes about 225 million years to complete one revolution around the Milky Way. This period is called a
cosmic year.
The first artificial satellite Sputnik was launched in .
1956
India launched its first satellite Aryabhatta on
April 19, 1975
The horizontal velocity that has to be imparted to a satellite at the determined height so that it makes a circular orbit around the planet is called
orbital velocity.
the satellite stays over the same spot all the time, this kind of orbit is called ‘.
geostationary
Orbital velocity can be calculated using the following formula
v=√{(GM)/(R+h)}
G = Gravitational constant (6.673 × 10^-11 Nm^2kg-²)
M = Mass of the Earth (5.972 x 10^24 kg)
R = Radius of the Earth (6371 km)
h Height of the satellite from the surface of the Earth.
Can you calculate the orbital velocity of a satellite orbiting at an altitude of 500 km?
Data: G=6.673 x 10-“ SI units;
M=5.972\times10^{24}kg
h=500000m
R=6371000m
Ans: v=7613 ms^-1 or 7.613 kms^-1
________ is the condition in which people or objects appear to be weightless. The effects of microgravity can be seen when astronauts and objects float in space. Micro- means very small, so microgravity refers to the condition where gravity ‘seems’ to be very small.
Microgravity
Time taken by a satellite to complete one revolution round the Earth is called .
time period
T=2πr/v
2π(R+h) T= -------------
√{(GM)/(R+h)}
At an orbital height of 500 km, find the orbital period of the satellite.
T= 5667 s
T=~95min
All stars appear to us as moving from east to west, where as there is one star which appears to us stationary in its position. It has been named as Pole star. The pole star appears to us as fixed in space at the same place in the sky in the north direction
because it lies on the axis of rotation of the Earth which itself is fixed and does not change its position in space. It may be noted that the pole star is not visible from the southern hemisphere.
Kepler was able to summarize the carefully collected data of his mentor,
Tycho Brahe
Kepler First Law - The Law of Ellipses
All planets revolve around the Sun in elliptical orbits with Sun at one of their foci.
Second Law - The Law of Equal Areas
The line connecting the planet and the Sun covers equal areas in equal intervals of time
Third Law - The Law of Harmonies
The square of time period of revolution of a planet around the Sun is directly proportional to the cube of the distance between sun and the planets.
As great as the ISS’ scientific achievements are, no less in accomplishment is the international co-operation which resulted in the construction of the ISS. An international collaboration of five different space agencies of 16 countries provides, maintains and operates the ISS. They are: _________ are also part of the consortium.
NASA (USA), Roskosmos (Russia), ESA (Europe), JAXA (Japan) and CSA (Cananda). Belgium, Brazil, Denmark, France, Germany, Italy, Holland, Norway, Spain, Sweden, Switzerland and the UK
The period of revolution of planet A around the Sun is 8 times that of planet B. How many times is the distance of planet A as great as that of planet B?
4
The Big Bang occurred ______years ago.
(a) 13.7 billion
The speed of Sun in km/s is
250 km/s
The rotational period of the Sun near its poles is
36 days
- The third law of Kepler is also known as the Law of
Harmonics
