**Galaxies are flat because of their rotation**. All of the stars, planets and other objects in a galaxy are rotating around the core of the said galaxy, and the conservation of angular momentum allows these objects to spread outward, but not any other direction, which is why they are flat.

**The Sun is not at the centre of the Earth's orbit**.

Why not circular? **Orbits are eliptical because of Newtons Law of Gravity** (bodies attract each other in proportion to their mass and inversly proportional to the square of the distance between them). All worked out by Kepler some years ago. A circular orbit is a special (and very unlikely) case of an eliptical orbit.

The **Gaussian constant**, k, is defined in terms of the Earth's orbit around the Sun. The Newtonian constant, G, is defined in terms of the force between two two masses separated by some fixed distance.

Circle

the law of harmonies

However, it is unknown if it is entirely habitable, as it is receiving slightly more energy than Earth and could be subjected to a runaway greenhouse effect. The Kepler space telescope identified the exoplanet, and its discovery was announced by NASA on 23 July 2015.

Kepler-452b.

Discovery | |
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Temperature | T_{eq}: 265 K (−8 °C; 17 °F) |

torus-shaped

A planet's orbital speed changes, depending on how far it is from the Sun. The closer a planet is to the Sun, **the stronger the Sun's gravitational pull on it, and the faster the planet moves**. The farther it is from the Sun, the weaker the Sun's gravitational pull, and the slower it moves in its orbit.

nearer the Sun

**Galaxies are flat because of their rotation**. All of the stars, planets and other objects in a galaxy are rotating around the core of the said galaxy, and the conservation of angular momentum allows these objects to spread outward, but not any other direction, which is why they are flat.

Kepler's Law MCQs for NEET

Kepler's Third Law: This law states that **the square of the time period (P) is directly proportional to the cube of the semi-major axis of its orbit**. P^{2} ∝ a^{3}. Q1: When a planet orbits the Sun, one of the foci of the elliptical orbit is. The axis. The perihelion.

**Most images you see of the solar system are 2D** and all planets orbit in the same plane.

The Sun is at one focus. The planet follows the ellipse in its orbit, meaning that the planet to Sun distance is constantly changing as the planet goes around its orbit. Kepler's Second Law: **the imaginary line joining a planet and the Sun sweeps equal areas of space during equal time intervals as the planet orbits**.

Ultimately, planetary ring systems are flat **because of the oblate (equatorially bulging) shapes of planets, which creates an asymmetric gravity field around the planets**. Stellar debris disks don't have these asymmetric gravity fields. They are flat, ultimately, because of the large angular momentum of the disk itself.

**With Ptolemy's mathematical tools, excenter and equant, trying to fit parameters with observations as well as possible**, he discovered the Law of Areas (now called the Second Kepler's Law). In this intermediate model the planets moved on circles but instead of having constant speed, they obeyed the Law of Areas. 9.

orbital calculations

In orbit. The eccentricity of an elliptical orbit is **a measure of the amount by which it deviates from a circle**; it is found by dividing the distance between the focal points of the ellipse by the length of the major axis.

Explanation: When a plane is perpendicular to a reference plane, **its projection on that plane is a straight line**. When a plane is parallel to a reference plane, its projection on that plane shows its true shape and size.

Kepler's laws are three laws of planetary motion discovered by Johannes Kepler, a German astronomer, in the early seventeenth century. Kepler's first law states that **a planet moves in an elliptical orbit around the Sun**, which is located at one of the two foci of the ellipse.

Dated : 26-May-2022

Category : Education