Evolution, Evolutionary history of Life on Earth and Geologic Time ScaleEvolutionEvolution is change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules.All life on Earth shar…
Moonrise seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
Spiral Galaxy NGC 24This shining disc of a spiral galaxy sits approximately 25 million light-years away from Earth in the constellation of Sculptor. Named NGC 24, the galaxy was discovered by British astronomer William Herschel in 1785, and measures some 40 000 light-years across.This picture was taken using the NASA/E…
Abiogenesis - Origins of Life on EarthAbiogenesis or biopoiesis or OoL (Origins of Life), is the natural process of life arising from non-living matter, such as simple organic compounds. It is thought to have occurred on Earth between 3.8 and 4.1 billion years ago. Abiogenesis is studied through a combination of laboratory experiments a…
Sunset seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
Reflection Nebula BFS 29NASA's Wide-field Infrared Survey Explorer, or WISE, captured this colorful image of the nebula BFS 29 surrounding the star CE-Camelopardalis, found hovering in the band of the night sky comprising the Milky Way. Most of the gas and dust in this image cannot be seen directly in visible light, but WI…
Origin of water on EarthThe origin of water on Earth, or the reason that there is clearly more liquid water on Earth than on the other rocky planets of the Solar System, is not completely understood. There exist numerous more or less mutually compatible hypotheses as to how water may have accumulated on Earth's surface ove…
Clouds over Pacific Ocean seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
MercuryMercury is the smallest and innermost planet in the Solar System. Its orbital period (about 88 Earth days) is less than any other planet in the Solar System. Seen from Earth, it appears to move around its orbit in about 116 days. It has no known natural satellites. It is named after the Roman deity …
Late Heavy BombardmentThe Late Heavy Bombardment (abbreviated LHB and also known as the lunar cataclysm) is an event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, corresponding to the Neohadean and Eoarchean eras on Earth. During this interval, a disproportionately large number of asteroids ar…
Earth seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
Herbig Haro 32HH 32 is an excellent example of a "Herbig-Haro object," which is formed when young stars eject jets of material back into interstellar space. This object, about 1,000 light-years from Earth, is somewhat older than Hubble's variable nebula, and the wind from the bright central star has already clear…
Formation of the MoonSeveral mechanisms have been proposed for the Moon's formation 4.527 ± 0.010 billion years ago, some 30–50 million years after the origin of the Solar System. Recent research presented by Rick Carlson indicates a slightly lower age of between 4.40 and 4.45 billion years. These mechanisms included th…
Sun's reflection on Atlantic Ocean seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
Planetary Nebula NGC 6826NGC 6826's eye-like appearance is marred by two sets of blood-red 'fliers' that lie horizontally across the image. The surrounding faint green 'white' of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the centre of the green o…
Early Earth - Theia collisionThe giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact suggests that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago, in the Hadean eon; about 20 to 100 million years …
Aurora seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: ESA/NASA…
The Crab PulsarThe Crab Pulsar (PSR B0531+21) is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054. Discovered in 1968, the pulsar was the first to be connected with a supernova remnant.The Crab …
Hadean: the first eon in Earth's historyThe Hadean is a geologic eon of the Earth, and lies before the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago. The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-…
Clouds over South Pacific Ocean seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: ESA/NASA…
Planetary Nebula NGC 2440The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the center. Our Sun will eventually burn out and s…
Early EarthThe early Earth is loosely defined as Earth in its first one billion years, or gigayear. On the geologic time scale, this comprises all of the Hadean eon (starting with the formation of the Earth about 4.6 billion years ago), as well as the Eoarchean (starting 4 billion years ago) and part of the Pa…
Moon seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: ESA/NASA…
Hubble Finds Planet Orbiting Pair of StarsThis artist's illustration shows a gas giant planet circling a pair of red dwarf stars. The Saturn-mass planet orbits roughly 300 million miles from the stellar duo. The two red dwarf stars are a mere 7 million miles apart.Astronomers using NASA's Hubble Space Telescope, and a trick of nature, have …
Earth FormationThe oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago (Gya). By 4.54±0.04 Gya the primordial Earth had formed. The formation and evolution of the Solar System bodies occurred along with those of the Sun. In theory, a solar nebula partitions a volume out of a molec…
Typhoon Lionrock seen from the International Space StationISS, Orbit of the EarthAugust 2016Image Credit: NASA/ESA…
Sirius - the brightest star in the Earth's night skyThis Hubble Space Telescope image shows Sirius A, the brightest star in our nighttime sky, along with its faint, tiny stellar companion, Sirius B. Astronomers overexposed the image of Sirius A [at centre] so that the dim Sirius B [tiny dot at lower left] could be seen. The cross-shaped diffraction s…
EarthEarth (otherwise known as the world, in Greek: Gaia, or in Latin: Terra) is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.According to radiometric dating and oth…
Cassiopeia AThis image taken with the NASA/ESA Hubble Space Telescope provides a detailed look at the tattered remains of a supernova explosion known as Cassiopeia A (Cas A). It is the youngest known remnant from a supernova explosion in the Milky Way. The Hubble image shows the complex and intricate structure …
Martian Sand DuneTwo sizes of wind-sculpted ripples are evident in this view of the top surface of a Martian sand dune. Sand dunes and the smaller type of ripples also exist on Earth. The larger ripples -- roughly 10 feet (3 meters) apart -- are a type not seen on Earth nor previously recognized as a distinct type o…
Gale Crater Lake on Mars, 3 billion years agoThis illustration depicts a lake of water partially filling Mars' Gale Crater, receiving runoff from snow melting on the crater's northern rim. Evidence of ancient streams, deltas and lakes that NASA's Curiosity Mars rover mission has found in the patterns of sedimentary deposits in Gale Crater sugg…
