Planets of the solar system - class-VII

Mean solar day is the time interval between two successive noon when sun passes through zenith point (meridian).

Time taken by light to reach the earth from the sun is, 

Ursa Major constellation lies in the northern sky. Its name means “the great bear,” or “the larger bear,” in Latin. The smaller bear is represented by Ursa Minor. Its brightest stars form the Big Dipper asterism, one of the most recognizable shapes in the sky, also known as the Plough.

Ursa Major is called as Saptarishi as it has seven prominent stars.

• Sun is star, which emits light from its own sources of energy. Remaining options Earth, Jupiter,Saturn and Venus are planets that revolve around the Sun and shine by the light of Sun.
• Hence, Sun is the odd one in given options.

Galileo observed that Venus goes through a full set of phases, which is only possible if Venus orbits the Sun. This observation directly contradicted the Ptolemaic (geocentric) model, which could not account for the full range of phases.

Most of the planets orbit the Sun very near the same plane in which the Earth orbits, the ecliptic.
The orbits of the planets are ellipses with the Sun at one focus, though all except Mercury are very nearly circular. The orbits of the planets are all more or less in the same plane (called the ecliptic and defined by the plane of the Earth's orbit). The ecliptic is inclined only 7 degrees from the plane of the Sun's equator.
Hence, the statement is true.

Jupiter revolves or orbits around the Sun once every 11.86 Earth years, or once every 4,330.6 Earth days. Jupiter travels at an average speed of 29,236 miles per hour or 47,051 km per hour in its orbit around the Sun.
Hence, the planet Jupiter takes 12 years to go around the Sun.

The distance between the sun and the earth is $149,600,000 km$ which is approximately equal to $150$ million kilometers.

Sun is regarded as the chief of solar system. It is because all of the other planets circle around it due to the gravitational pull because of its enormous mass.

The mean distance between the Earth and Sun as well as the distances within the solar system is represented by astronomical units.
One astronomical unit (AU) represents:
1 AU = 149,597,870.700 kilometers (or 149,597,870,700 meters)
An astronomical unit is the mean distance between the Earth and the Sun.

Out of these fours mercury takes minimum time to revolute one round. It takes $88$ days to do so.

Day and night are caused by  rotation of earth.

Every planet in solar system except venus and uranus rotates frm west to east so uranus rotates from east to west.

A unique feature of Uranus is that it appears to roll along its orbital plane. This is because it has a highly tilted axis which makes it almost parallel to its orbital motion and the planet appears to roll.

Jupiter is the fastest rotating planet. It take only 9 hours and 55 min to complete one rotation about its own axis.

From summer solstice (June 21), the Sun starts moving towards the South and from winter solstice (December 22), the Sun starts moving towards North. So during summer solstice, it is in the south eastern part and in winter solstice it is in the north eastern part. However, there are 2 days, i.e., March 21 and September 23, when the Sun rises exactly in the East.

With the development of the heliocentric model by Nicolaus Copernicus in the 16th century, the sun was believed to be the center of the Universe, with the planets (including Earth) and stars orbiting it. 

Every planet is at a different distance from the Sun and has a fixed orbit in which it revolves around the Sun. The Sun"s gravitational force holds the planets in this place and they do not collide with each other as their orbits are non-intersecting.

As the distance between the Sun and the planet increases, the time taken by the planet to complete one revolution around the Sun also increases as the planet has to cover more distance as compared to the planets before it.

Just like moon, Venus too rotates from East to West. Thus, only that part of Venus is visible to us which reflects the light from the Sun towards us. Hence, the Venus appears to show phases because the Earth and Venus rotate in opposite direction.

The autumnal equinox in the Northern Hemisphere typically occurs on September 22 or 23. September 23 is the standard date used in most educational contexts.

Planets are solid heavenly bodies which revolve around the Sun in closed elliptical paths. A planet is made of rock and metal and produces no light of its own. A planet shines because it reflects the light of the Sun. Since, the planets are much nearer to the stars, they appear to be big and do not twinkle at night. The planets move around the Sun from West to East, so the relative positions of the planets keep changing day by day. They are very small compared to the sun and other stars. 
Hence, the star appears to remain in a fixed position with respect to each other whereas the distance between the planets keep changing constantly.

Planets are solid heavenly bodies which revolve around the Sun in a closed elliptical paths. A planet is made of rock and metal and produces no light of its own. A planet shines because it reflects the light of the Sun. Since, the planets are much nearer to the stars, they appear to be big and do not twinkle at night.
Hence, the statement is true.

Using Newton's Law of Universal Gravitation, F = G * (m1 * m2) / r^2. Plugging in G = 6.67e-11, m1 = 1.9e27, m2 = 1.99e30, and r = 7.8e11, the calculation yields approximately 4.1e23 N.

Kepler's Third Law of Planetary Motion states that the square of the orbital period is proportional to the cube of the semi-major axis of the orbit (T^2 proportional to r^3). Therefore, T1/T2 = (r1/r2)^(3/2).

Planets are like spheres. Volume of a sphere is given by, 
V = $\displaystyle{\frac{4}{3}\pi r^3}$ 
Let the r$ _1$, r$ _2$ be radii of the Jupiter and the Earth respectively. 
r$ _1$ $= 11r _2$ _(1)
Volume of Jupiter, V$ _1$ = $\displaystyle{\frac{4}{3}\pi r^3 _1}$ _(2) 
Volume of Earth, V$ _2$ = $\displaystyle{\frac{4}{3}\pi r^3 _2}$ _(3) 
$\displaystyle{\frac{(2)}{(3)} \Rightarrow \frac{V _1}{V _2} = \frac{\frac{4}{3}\pi r _1^3}{\frac{4}{3} \pi r _2^3} = \frac{r _1^3}{r _2^3}}$ 
$\displaystyle{\frac{V _1}{V _2} = \frac{r _1^3}{r _2^3} = \frac{(11r _2)^3}{r _2^3} = (11)^3}$ = 1331 
Jupiter can accommodate 1331 number of Earths within it.

Earth spins about its own axis from west to east. In another word earth turns counter clockwise direction as viewed from north pole.

On Astronomical unit is the mean distance between earth and sun.

As earth is rotating on its own axis so its half part is exposed to sun cause day at that part and hidden half part suffers from darkness called night.

As earth is rotating on its own axis from west to east so, due to relative motion star appears to move from east to west.

Ans : Venus

Planets that rotate rapidly experience a centrifugal force that causes them to bulge at the equator and flatten at the poles. Jupiter has a very fast rotation period, leading to this oblate shape.

Neptune takes maximum time to complete one revolution as it is the farthest planet.

Ans: Elliptical 

Solar day is the time taken by earth to complete one rotation about its axis with respect to sun. Sidereal day is the time taken by earth to complete one rotation about its axis with respect to distant star. There is a difference of $4$ minutes between solar day and sidereal day. Solar day is longer as earth has to rotate greater angle to attain same position with respect to sun due to its own motion (revolution) round the sun. Its position with respect to distant star remains almost fixed.

A star and all the objects travelling around it — planets, moons, asteroids, comets and meteoroids constitute a solar system. Our solar system is located in Milky Way galaxy. Sun is the star of our solar system. The eight planets and their natural satellites, dwarf planets and their satellites, as well as asteroids, comets and other celestial bodies revolve around the sun.

Order of the planets of solar system on the basis of their size is given as following: -

1. Jupiter - Its diameter is 69,911 km.
   
2. Saturn - Its diameter is 58,232 km.
   
3. Uranus - Its diameter is 25,362 km.
   
4. Neptune - Its diameter is 24,622 km.
   
5. Earth - Its diameter is 6,371 km.
   
6. Venus- Its diameter is 6,052 km.
   
7. Mars - Its diameter is 3,390 km.
   
8. Mercury- Its diameter is 2,440 km.

A pole star is a visible star, which lies approximately directly overhead when viewed from earth's north pole or south pole. In practice the term pole star usually refers to polars, which is the current northern pole star, also known as north star. The south celestial pole lacks a bright star like polarise to mark its position.

Minor planet is a term used to refer to a celestial object – that is not a planet or comet – which orbits the Sun. Found in 1801, Ceres, also known as a dwarf planet, was the first minor planet discovered. 

Kepler's law states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. So a planet moves most quickly when it is closest to the sun,as it have to cover more distance in same time but it again  slows down as it moves farther away as covering distance is less.