planet

(noun)

A body which orbits the Sun directly and is massive enough to be in hydrostatic equilibrium (effectively meaning a spheroid) and to dominate its orbit. The eight planets in the Solar System are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was considered a planet until 2006 and has now been reclassified as a dwarf planet.

Related Terms

Examples of planet in the following topics:

  • 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.

  • 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.

  • Ocean Floor

    • Microbial life plays a primary role in regulating biogeochemical systems in virtually all of our planet's environments, including some of the most extreme, from frozen environments and acidic lakes, to hydrothermal vents at the bottom of deepest oceans, and some of the most familiar, such as the human small intestine.
    • For example, nitrogen which makes up 78% of the planet's atmosphere is "indigestible" for most organisms, and the flow of nitrogen into the biosphere depends on a microbial process called fixation.

  • Microbes and Ecosystem Niches

    • Microbial life is amazingly diverse and microorganisms quite literally cover the planet.
    • In fact, it has been estimated that there are 100,000,000 times more microbial cells on the planet than there are stars in the observable universe!

  • Double-Stranded DNA Bacteriophages

    • The dsDNA tailed phages, or Caudovirales, account for 95% of all known phages and possibly make up the majority of phages on the planet.
    • The Double-Stranded DNA (dsDNA) tailed phages, or Caudovirales, account for 95% of all the phages reported in the scientific literature, and possibly make up the majority of phages on the planet.

  • Sources and Sinks of Essential Elements

    • Although the Earth receives energy from the Sun, the chemical composition of the planet is more or less fixed.

  • Classification of Microorganisms

    • By learning to recognize certain patterns and classify them into specific groups, biologists are better able to understand the relationships that exist among a variety of living forms that inhabit the planet.

  • Types of Microorganisms

    • Microorganisms make up a large part of the planet's living material and play a major role in maintaining the Earth's ecosystem.