Earth

Earth, our home planet, is a beautiful blue and white ball when seen from space. The third planet from the Sun, it is the largest of the inner planets. Earth is the only planet known to support life and to have liquid water at the surface. Earth has a substantial atmosphere and magnetic field, both of which are critical for sustaining life on Earth. Earth is the innermost planet in the solar system with a natural satellite – our Moon. Explore our beautiful home planet – unique in our solar system - through the links in this section.

Coral animals build reefs in warm, tropical seawater. However, <a href="/earth/changing_planet/ocean_temperatures_intro.html&dev=1/k=/h/neptune/cli_models4.html">seawater can be too warm</a> for their liking. If waters get too warm, coral animals lose the algae that live within their little bodies, a process called coral bleaching. Without the algae, corals have less nutrition. Unless cooler temperatures return, allowing algae to return, the coral dies.<p><small><em>Credit: UNC</em></small></p>An artist's rendering of the moment of impact of a massive <a href="/our_solar_system/meteors/meteors.html&dev=1/k=/h/neptune/cli_models4.html">meteorite</a> at the end of the Cretaceous (at the end of the <a href="/earth/geology/hist_mesozoic.html&dev=1/k=/h/neptune/cli_models4.html">Mesozoic Era</a>). Many scientists have concluded for decades that a meteorite four to six kilometers in diameter impacted the Earth at this time, resulting in a <a href="/earth/past/KTextinction.html&dev=1/k=/h/neptune/cli_models4.html">mass extinction of dinosaurs</a> and many other life forms. Recent research suggests that perhaps <a href="/headline_universe/olpa/chicxulub.html&dev=1/k=/h/neptune/cli_models4.html">massive volcanic eruptions</a> may be been responsible for the extinction.<p><small><em>Courtesy of Don Davis, NASA</em></small></p>How did life evolve on <a href="/earth/earth.html&dev=1/k=/h/neptune/cli_models4.html">Earth</a> during the <a href="/earth/past/Archean.html&dev=1/k=/h/neptune/cli_models4.html">Archean</a>, when the <a href="/sun/sun.html&dev=1/k=/h/neptune/cli_models4.html">Sun</a> was about 25% weaker than today? The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&dev=1/k=/h/neptune/cli_models4.html">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&dev=1/k=/h/neptune/cli_models4.html">greenhouse</a> gas concentration was the same as today. <a href="http://www.manchester.ac.uk/aboutus/news/display/?id=10798">Researchers</a> studying the <a href="/physical_science/physics/atom_particle/isotope.html&dev=1/k=/h/neptune/cli_models4.html">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&dev=1/k=/h/neptune/cli_models4.html">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&dev=1/k=/h/neptune/cli_models4.html">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&dev=1/k=/h/neptune/cli_models4.html">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&dev=1/k=/h/neptune/cli_models4.html">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</em></small></p>This iconic image of Earth rising above the surface of the <a href="/earth/moons_and_rings.html&dev=1/k=/h/neptune/cli_models4.html">Moon</a>, was taken on December 24, 1968 by astronauts on the <a href="/space_missions/apollo8.html&dev=1/k=/h/neptune/cli_models4.html">Apollo 8 mission</a>. Apollo 8 was the first <a href="/space_missions/manned.html&dev=1/k=/h/neptune/cli_models4.html">manned mission</a> to the Moon, and entered into lunar orbit on Christmas Eve. That evening, the astronauts held a live broadcast from lunar orbit, in which they showed pictures of the Earth and moon as seen from their spacecraft.<p><small><em> Image courtesy of NASA</em></small></p>Greenland's <a href="http://www.windows2universe.org/earth/polar/cryosphere_glacier1.html">ice sheet</a> saw a record <a href="http://www.windows2universe.org/headline_universe/olpa/greenland_10dec07.html">melt</a> in July 2012. Scientists studying this event have found that this melting event was triggered by an influx of unusually warm air and amplified by the presence of a blanket of thin low-level <a href="http://www.windows2universe.org/earth/Atmosphere/cloud.html">clouds</a> which pushed temperatures up above freezing. For more information see the <a href="http://www.news.wisc.edu/21638">press release</a> from the University of Wisconsin Madison.<p><small><em>Image courtesy of University of Wisconsin-Madison</em></small></p>As permafrost thaws, the land, atmosphere, water resources, ecosystems, and human communities are affected. Coastal areas and hillsides are vulnerable to erosion by thawing of permafrost. Thawing permafrost also causes a positive feedback to global warming, as carbon trapped within the once-frozen soils is released as <a href="/physical_science/chemistry/methane.html&dev=1/k=/h/neptune/cli_models4.html">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html&dev=1/k=/h/neptune/cli_models4.html">greenhouse gas</a>. Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html&dev=1/k=/h/neptune/cli_models4.html">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the USGS</em></small></p>

Explore Earth

Earth's Interior and Surface

Earth, the largest and densest rocky planet, was formed about 4.5 billion years ago. The Earth's ...Read more

Atmosphere

The atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surrounds ...Read more

Magnetosphere

The Earth has a magnetic field with north and south poles. The magnetic field of the Earth ...Read more

Moon

The Earth's one natural satellite, the Moon, is more than one quarter the size of Earth itself ...Read more

Earth's Polar Regions

Do you wonder what Earth's Polar Regions are like? Where do polar bears live? Where do penguins ...Read more

Climate and Global Change

Warm near the equator and cold at the poles, our planet is able to support a variety of living ...Read more

Water (The Hydrosphere)

Water is found in many places on Earth including on the surface of the planet, within rocks ...Read more

Life and Ecology (The Biosphere)

What is life? Why is there life on Earth, but not on any other planets in the solar system ...Read more

Natural Hazards

The United Nations estimated that between 1994-2015, there were 6,873 natural disasters worldwide, ...Read more

More about Earth

Historical Events

Full Earth and Space Science    History Calendar (Members only)

Teacher Opportunities

Full Teacher Events Calendar (Educator Members only)

Did you know?

Did you know that lunar eclipses are produced by the Earth casting its shadow on the Moon?

Do you know how photosynthesis works?

 

Earth and Space Science Concept of the Day

Do you know what this word or phrase means?

Spreading ridge
xSpreading ridge : An oceanic spreading ridge is the fracture zone along the ocean bottom where molten mantle material comes to the surface, thus creating new crust.

Click on the word to find out!

Research Highlights

New Findings Indicate Sediment Composition Affected the Strength of Sumatran Earthquake

Sumatra experiences frequent seismic activity because it is located near the boundary of two of Earth's tectonic plates. Earthquakes occur at 'subduction zones,' such as the one west of Indonesia, when...Read more


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