Stars And The Solar System - Class 8 Physics - Extra Questions

True,Mercury is the smallest planet of the solar system.Mercury measures 4879 km along its equator. Just for comparison, Earth is 12,742 km across. So Mercury is only 38% the diameter of Earth. In terms of volume, its even less. Mercury has only 0.05 the volume of the Earth.

The other names for Mercury is Budh, for Venus it is Shukra, for Mars it is Mangal for Jupiter it is Brihaspati and for Saturn it is Shani.

Jupiter is the largest planet of the solar system.

(a) The planet which is farthest from the Sun is Neptune.
(b) The planet which appears reddish in colour is Mars.
(c) A group of stars that appear to form a pattern in the sky is known as constellation.
(d) A celestial body that revolves around a planet is known as satellite.
(e) Shooting stars are actually not stars.
(f) Asteroids are found between the orbits of Mars and Jupiter.

If venus is visible as evening star i.e. after sunset, it appears in the western sky.

The given sketch in the question is incorrect. The order of the planets and the position of asteroid belt is wrong in the sketch given in the question.

The sun and the celestial bodies that revolve around it forms the solar system. It consists of sun, planets, satellites, asteroids, comets, meteors and meteorites. Halley's comet and the moon are two examples of celestial bodies that are part of the solar system but not planets.

Ursa major is a group of seven stars. Pole stars can be found by extending the line connecting last two stars 

Sun is nearer to earth as composed to distance of other stars from the earth, the sun appears to be bigger and brighter.

The great red spot is a persistent zone of high pressure, producing an anticyclonic storm on the planet Jupiter.

In our solar system Saturn is the only one planet which has highest number of satellites.

Mercury is the smallest and nearest planet to the sun of the solar system.

The outermost layer of the earth is called the crust. It constitutes less than 1% of the earth's volume. It is made up of soil, rocks and different types of minerals and mostly covered with water.

The four innermost planets Mercury, Venus, Earth and Mars have some features in common with the earth and hence they are called Terrestrial Planets.

Characteristics of the Jovian Planet are as follows :
1. They all are gaseous bodies.
2. They have ring systems around them.
3. They have a large number of natural satellites.

According to the solar system ,Mercury is the nearest planet to the sun in solar system.

Jupiter is the first planet of Jovian group (Jovian is derived from Jupiter and the first to be observed using a telescope).

Comets- Comets are the objects which move in highly elongated orbits around the sun. Their central part is solid while outer part is made up of frozen gases like ammonia, Methane, water vapours etc. However it is not a star. Comets are heavenly bodies which revolve around the sun in highly elliptical path. Usually comets come no closer than a few million km to the sun. Their mass is very less. They many be even millionth part of the mass of earth. So far only $$1000$$ comets could be seen. It is believed that they may be more than $$100$$ Arab in number. Most of the comets revolve much beyond the orbit of its outer most planet. Thus, generally, they are not visible from the earth. Normally when they are away from the sun, they are neither visible nor they come close to the sun, the frozen gases vapourize and start glowing. As the distance from the sun reduces, the vaporisation increases and hence the length of the tail increases. Due to the presence of this tail, it is also called a "Puchchal Tara". We can see comets when they are closer to the sun because in this position they are closet to the earth too.

The full form of ISRO is the Indian Space Research Organisation. It is the main space research institute in India.

On $$28.10.2007$$ the moon is visible for $$13\ hr\ 34\ min$$.

Satellite Launch Vehicle

The length of the tail gets bigger in size as it approaches the sun. The tail of a comet is always directed away from the sun. 

The brightness of a meteor is extremely small compared to that of the sun, therefore, it is not seen during day time.

The pole star is always situated at the northern end of the axis of rotation of the Earth. So the given diagram represents the position of the pole star for the above given diagram.

No,the moon will not be visible at the same position.It is so because, the moon revolves around the earth.As a result, it's position always changes. So, the moon will not be seen at the same position.

The Moon doesn't emit (give off) light itself, the 'moonlight' we see is actually the Sun's light reflected off the lunar surface. So, as the Moon orbits the Earth, the Sun lights up different parts of it, making it seem as if the Moon is changing shape.

C is the position of sun because the part beside it is day in earth. The light will fall in that region. 

Temperature on the Moon's surface fluctuate dramatically from blistering heat 100C to frigid cold during the night -173C. With no atmosphere there is no wind.Moon has very tenuous or negligible atmosphere and the lunar gases are easily lost to the atmosphere because of Moon's low gravity light atoms such as helium receive enough energy from solar heating so that they escape in just a few hours.

The given statement is True. It's just that the amount of time it takes the moon to complete a rotation about its axis is the same it takes to revolve around our planet — about 27 days. As a result, the same lunar hemisphere always faces the Earth.

Life may no longer exist because some special environmental conditions are needed for the existence and continuation of life on the earth. The right distance of earth from the Sun is necessary so that it has right temperature range, the presence of water and suitable atmosphere and a blanket of ozone.

The correct order from centre is : Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune .

1. The geostationary orbit of the satellite is used for television broadcasting that operates above the equator.
2. Springtide is a tide just after a new or full moon when there is the greatest difference between high and low water and is formed twice a month.
3. A meteorite is a solid piece of debris from a source such as an asteroid or a comet or a meteor, which originates in outer space and is not burnt in the atmosphere and survives its impact with the Earth's surface.
   
4. Eclipse is an obscuring of the light from one celestial body by the passage of another between it and the observer or between it and its source of illumination forming shadow.
5. A comet is a celestial object consisting of a nucleus of ice and dust and, when near the Sun, a ‘tail’ of gas and dust particles pointing away from the Sun.

1. Locate the two end stars of Ursa Major. 
2. Imagine a straight line passing through these stars as shown in the figure alongside.
3. Extend this imaginary line towards the north direction. This is pole star.

After full moon day, every night the size of the bright part of the moon appears to become thinner and thinner.

There is a large gap in between the orbits of Mars and Jupiter . This gap is occupied by a large number of small objects that revolve around the Sun. These are called asteroids.

There is a large gap between the orbits of Mars and Jupiter. This gap is occupied by a large number of small bodies that revolve around the sun. These bodies are called asteroids. They are large rocks flying around sun but they are not big enough to be called a planet.Hence asteroids have failed to assemble into a planet.

No, all the stars do not move in the sky. The Pole star is located above the axis of rotation of the Earth in the north direction. Thus, it appears stationary at a point in the sky, it does not move in the sky. All other stars in the sky appear to move from East to West in the sky.

Mars is commonly referred to as the "Red Planet" because it appears red or orange in the sky. 

The distance of the stars from the Earth is very large. Thus, it is convenient to express these distances in bigger units like light-years. If a star is located eight light-years away from the Earth, it means that the light from that star reaches after eight years. In other words, the light of the star which we are seeing today started from that star eight years ago.

Astronomers have estimated that the universe was formed about $$13.7$$ billion years ago.

Earth is a fairly big body and its shadow can completely cover the whole moon. Moon has to pass through a very large shadow of the earth hence  lunar eclipse is fairly a common phenomenon. Solar eclipse is not so 
common because many a times the shadow of the moon does not reach the  earth

Ursa major has 7 prominent stars. Orion has 7 or 8 Casiopeia has 5 and Leo major has 9 prominent stars. The stars that shine brightly and make the constellation distinctively visible are called prominent stars of a constellation. The other stars of the constellation are also present but however they are not bright enough to be visible by the naked eye. Hence those prominent stars are used to mark a constellation.

(a) F

Distance between stars are very large in magnitude. Hence a new unit is required so that the value of distance is not too big and is sensible. A light year is defined as the distance travelled by light in one year. 

The diagram shows the relative positions of prominent stars in Ulsa Major and Orion. Ulsa Major can used to find location of Pole Star and Orion can be used to find position of Sirius.

The Earth is the only planet in the solar system on which life is known to exist. Some special environmental conditions are responsible for the existence and continuation of life on the Earth. These include just the right distance from the Sun, so that it has the right temperature range, the presence of water and suitable the atmosphere and a blanket of ozone.

Indian space program is conducted under the authority of ISRO. ISRO stands for Indian Space Research Organisation. It was established on $${15}^{th}August,1969$$, with a motto of 'Space Technology in the service of Humankind". Its current administration is Dr. K. Sivan, and is currently running on a budget of $$15$$ billion USD. ISRO started its legacy on $${19}^{th}April,1975$$ by launching its first satellite, $$Aryabhata$$.

Artificial satellites use solar panels to utilize the energy of the incident light from the sun to power their instruments inside it. The energy is inexhaustible and free throughout. Hence it is imperative to use solar energy through solar panels to provide electricity to instruments in artificial satellites.

A) Aryabhatta was first Indian satellite launched by India on 19 April 1975.
B) Bhaskara-1 was the first experimental remote sensing satellite built by India. The primary objectives of Bhaskara-1 mission was to conduct earth observation experiments that would yield useful data in the areas of meteorology, hydrology and forestry using a two band TV camera system  in two wavelength spectrum. It also was employed to conduct ocean surface studies using a three chain radiometer operating at microwave frequencies.
C) Ariane Passenger Payload Experiment (APPLE) was India's first Geostationary experimental communication satellite launched on June 19, 1981 by Ariane, a launch vehicle of the European Space Agency (ESA).
D) RH-75, the first sounding rocket developed by India, was launched from TERLS on November 20, 1967.

The Big Bang theory is a model to explain the origin of the Universe. According to it, the Universe was created in a massive explosion creating the majority of matter.  It is the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now—and it is still stretching.

Solar system is the family of the star Sun and its eight 8 planets revolving around the sun with their moons .

No, Two person cannot hear each other on moon because sound needs material or medium to travel . on moon their isn't any atmosphere so they unable to talk to each other

Since the star is 50 light-years away so the time it takes for light to travel from that star to earth is 50 years so we will see the explosion after 50 years. It depends on the age of the individual.

In Hindu cosmology, the universe is cyclically created and destroyed. Its cosmology divides time into four epochs or Yuga, of which the current period is the Kali Yuga.

It is generally known that the Indians believed in a cyclic universe. This idea is related to three other beliefs: (i), time is endless and space has infinite extension; (ii), earth is not the center of the universe; and (iii), laws govern all development, including the creation and destruction of the universe. It was believed that there are connections between the physical and the psychological worlds, and an equivalence existed between the outer cosmos and the inner cosmos of the individual. 

This project was started in 1948 by Mr. Albert Mayer of the USA who came to India as a warrior at a village called Mahewa in UP.

Yes, I have seen the moon at 12 in the afternoon.

Revolution of the earth around the sun is a natural periodic change. Periodic changes are those changes that repeat at a regular interval. Due to this natural periodic change, different seasons occur on the earth. It is natural because it cannot be manipulated by any external agent.

1 light year means the distance traveled by the light in one year. So, we will be able to see a star which is located 10 light years away from the Earth after ten years.

The orbital period (also revolution period) is the time a given astronomical object takes to complete one orbit around another object(generally sun).

(a) In the fifth century, Indian astrologer Aryabhatta gave the geocentric model to understand the motion of the planet.

The planets order according to their distance from earth are Venus, Mars, Mercury, Jupiter, Saturn, Uranus and Neptune.

The planets in order from the Sun based on their distance are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Increasing order of size of planets are Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn and Jupiter.

The planets - Mercury, Venus , Earth and Mars are called terrestrial planets as they have a rocky surface. These are the first four planets of our solar system.

A solid heavenly body which revolves around the Sun in a closed circular orbit is called a planet.

$$Phobos$$ and $$Deimos$$ are two satellites of Mars. 

 The moon changes its shape everyday over a period of one month and this repeats over and over again. These different shapes of the moon are called 'Phases of the Moon'. In reality, the moon does not change its shape at all.

In the solar system the planets are revolving about the sun and rotating about their axes in a counterclockwise direction and revolving from west to east.

Asteroids and dwarf planets.

Constellation has the following characteristics:

Saturn is known to have the largest number of natural satellites.

Planets: Neptune, Mercury.

$$(a)$$ Largest planet - Jupiter.

Asteroids are small, rocky objects that orbit the sun. They are much smaller than planets. Asteroids can also be considered as minor planets which can neither be classified either as a planet nor as a comet. The larger forms of asteroids are also known as planetoids. 

The first satellite launched in India was Arybhath in 19 April, 1975

Pole star is situated along the axis of rotation of earth over the North pole. Hence pole star isn't visible from the southern hemisphere.

A meteor is usually a very small celestial object that occasionally enters the earth's atmosphere. 

A transit of Mercury across the Sun takes place, when the planet Mercury passes directly between the Sun and a superior planet, becoming visible against the solar disk. During a transit, Mercury can be seen from Earth as a small black disk moving across the face of the Sun. The duration of such transits is usually measured in hours (the transit of 2012 lasted 6 hours and 40 minutes).

The Sun along with the eight planets, their moons, asteroids, comets and meteors constitute our solar system.

Earth is also called the blue planet.

Saturn has the maximum number of moons