planet

Examples of planet in the following topics:

• Kepler's Second Law

  • A line joining a planet and the Sun sweeps out equal areas during equal intervals of time .
  • In a small time the planet sweeps out a small triangle having base line and height.
  • Now as the first law states that the planet follows an ellipse, the planet is at different distances from the Sun at different parts in its orbit.
  • When the planet is close to the Sun it has a larger velocity, making the base of the triangle larger, but the height of the triangle smaller, than when the planet is far from the Sun.
  • One can see that the planet will travel fastest at perihelion and slowest at aphelion.

• Planetary Motion According to Kepler and Newton

  • As the planet moves closer to the Sun, it speeds up.
  • Newton theorized that the direction of a planet is always towards the Sun.
  • Therefore, by Newton's law, every planet is attracted to the Sun, and the force acting on a planet is directly proportional to the mass and inversely proportional to the square of its distance from the Sun.
  • The planet moves faster near the Sun so that the same area is swept out in a given time as it would be at larger distances, where the planet moves more slowly.
  • The green arrow represents the planet's velocity, and the purple arrows represent the force on the planet.

• Mars and a Biosphere

  • Mars, the fourth planet from the Sun, is currently undergoing a great deal of investigation concerning its capacity for maintaining life.
  • Mars is the fourth planet from the Sun and the second smallest planet in the Solar System.
  • The planet can be seen from Earth with the naked eye .
  • The planet is currently host to five functioning spacecraft: three in orbit—the Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter; and two on the surface—Mars Exploration Rover Opportunity and the Mars Science Laboratory Curiosity.

• Microbial Environments and Microenvironments

  • The extraordinary biological diversity among microbes reflects their ability to occupy every habitable environment on the planet.
  • Microorganisms are found on practically every habitable square inch of the planet.
  • Microorganisms are ubiquitous despite the fact that the planet is host to extraordinarily diverse environments.
  • Therefore, microbes have adapted to fill every ecological niche on the planet.
  • These evolutionary adaptations have allowed microbial life to extend into much of the Earth's atmosphere, crust, and hydrosphere (the water found over, under, and on the surface of a planet).

• Martian Biosignatures

  • A biosignature, a substance that provides scientific evidence of past or present life, is present in the form of fog on the planet Mars.
  • This mixture of gases has also been observed in the atmosphere of the planet Mars.
  • Due to scientific thought that this fog cannot be formed by a chemical process, logic concludes that there must be some source of life on the planet .
  • The probes took images of the planet while in orbit and also while actually on the surface of Mars.

• Kepler's First Law

  • Kepler's first law is: The orbit of every planet is an ellipse with the Sun at one of the two foci.
  • The orbit of every planet is an ellipse with the Sun at one of the two foci.
  • The dwarf planet Pluto, discovered in 1929, has an eccentricity of 0.25.
  • For a planet orbiting the Sun, $r$ is the distance from the Sun to the planet and $\theta$ is the angle between the planet's current position and its closest approach, with the Sun as the vertex.
  • Kepler's first law states this fact for planets orbiting the Sun.

• Satellites

  • It is technically correct to refer to a planet as a "satellite" of its parent star, though this is not common.
  • Formally classified natural satellites, or moons, include 176 planetary satellites orbiting six of the eight planets, and eight orbiting three of the five IAU-listed dwarf planets.
  • As of January 2012, over 200 minor-planet moons have been discovered.
  • Planets around other stars are likely to have natural satellites as well, although none have yet been observed.
  • Polar orbit: An orbit that passes above or nearly above both poles of the planet on each revolution.

• Terraforming Mars

  • The phrase "terraforming Mars" refers to the idea that the planet Mars could be altered in a way so that it could sustain human and terrestrial life .
  • The impact of terraforming Mars would be that in the face of global calamity, there would be a place outside of our planet that would be a safe haven for mankind.
  • Although Mars is most like Earth out of all the planets in our solar system, it is still highly unsuitable for life as we know it.
  • Scientists are focusing the least energy on solving this issue due to the amount of carbon dioxide on the planet.
  • Carbon dioxide is a greenhouse gas which means that once the planet begins to heat, the excess carbon dioxide will probably help keep the heat near the ground.

• Kepler's Third Law

  • Kepler's third law states that the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
  • The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit .
  • The third law, published by Kepler in 1619, captures the relationship between the distance of planets from the Sun, and their orbital periods.
  • where P is the orbital period of the planet and a is the semi-major axis of the orbit (see ).
  • Kepler's third law states that the square of the period of the orbit of a planet about the Sun is proportional to the cube of the semi-major axis of the orbit.

• Escape Speed

  • Imagine a situation in which a spaceship that does not have a propulsion system is launched straight away from a planet.
  • Let us assume that the only significant force that is acting on the spaceship is the force of gravity from the planet.
  • Where $G$ is the universal gravitational constant ($G = 6.67 \cdot 10^{-11} \text{m}^3\text{kg}^{-1}\text{s}^{-2}$), $M$ is the mass of the planet, $m$ is the mass of the spaceship, and $r$ is the distance of the spaceship from the planet's center of gravity.
  • Interestingly, if the spaceship were to fall to the planet from a point infinitely far away it would obtain a final speed of ses_e at the planet.
  • If the vehicle has a propulsion system to provide it with energy once it has left the surface of the planet, it is not necessary to initially meet escape speed requirements.