#AGE OF SPACE SERIES#

Designed to study the solar wind, as well as the sun's outer layers and interior structure, it has imaged the structure of sunspots below the surface, measured the acceleration of the solar wind, discovered coronal waves and solar tornadoes, found more than 1,000 comets, and revolutionized our ability to forecast space weather. The Solar and Heliospheric Observatory (SOHO), which last year celebrated 25 years in space, has been one of the most important solar missions to date. NASA lost contact with STEREO-B in 2014, which remained out of contact except for a brief period in 2016. In 2007, NASA's double-spacecraft Solar Terrestrial Relations Observatory (STEREO) mission returned the first three-dimensional images of the sun. In 2004, NASA's Genesis spacecraft returned samples of the solar wind to Earth for study. In 1990, NASA and the European Space Agency launched the Ulysses probe to make the first observations of its polar regions. Seven of them were successful, and analyzed the sun at ultraviolet and X-ray wavelengths and photographed the super-hot corona, among other achievements.

#AGE OF SPACE SERIES#

NASA launched a series of eight orbiting observatories known as the Orbiting Solar Observatory between 19. To learn more about how the sun and other stars work, after early observations using rockets, scientists began studying the sun from Earth orbit. Then, in 1543, Nicolaus Copernicus described a heliocentric (sun-centered) model of the solar system, and in 1610, Galileo Galilei's discovery of Jupiter's moons confirmed that not all heavenly bodies circled Earth.

Many believed the sun revolved around the Earth, with the ancient Greek scholar Ptolemy formalizing this 'geocentric' model in 150 B.C. (Image credit: Solar Orbiter: ESA/ATG medialab Parker Solar Probe: NASA/Johns Hopkins APL)Īncient cultures often modified natural rock formations or built stone monuments to mark the motions of the sun and moon, charting the seasons, creating calendars and monitoring eclipses. The ESA-NASA Solar Orbiter and NASA's Parker Solar Probe currently study the sun in unprecedented detail from a closer distance than any spacecraft before. Related: Space weather: Sunspots, solar flares & coronal mass ejections Matter from the corona is blown off as the solar wind. The corona generally ranges from 900,000 F (500,000 C) to 10.8 million F (6 million C) and can even reach tens of millions of degrees when a solar flare occurs. At the top is the super-hot corona, which is made of structures such as loops and streams of ionized gas. Next up is the chromosphere, which is hotter, up to 35,500 F (19,725 C), and is apparently made up entirely of spiky structures known as spicules typically some 600 miles (1,000 km) across and up to 6,000 miles (10,000 km) high.Īfter that is the transition region a few hundred to a few thousand miles thick, which is heated by the corona above it and sheds most of its light as ultraviolet rays. Temperatures in the photosphere range from 11,000 F (6,125 C) at the bottom to 7,460 F (4,125 C) at the top. It is about 300 miles (500 km) thick, although most of the light comes from its lowest third. The photosphere is the lowest layer of the sun's atmosphere, and emits the light we see. Two main kinds of solar convection cells exist - granulation cells about 600 miles (1,000 kilometers) wide and supergranulation cells about 20,000 miles (30,000 km) in diameter. Roiling 'convection cells' of gas dominate this zone. The convection zone reaches up to the sun's surface, and makes up 66% of the sun's volume but only a little more than 2% of its mass. Light from the core gets scattered in this zone, so that a single photon often may take a million years to pass through. Next is the radiative zone, which extends from the core to 70% of the way to the sun's surface, making up 32 % of the sun's volume and 48% of its mass. Although it only makes up roughly 2% of the sun's volume, it is almost 15 times the density of lead and holds nearly half of the sun's mass.

The core extends from the sun's center to about a quarter of the way to its surface. Beyond that is the solar wind, an outflow of gas from the corona. The solar atmosphere above that consists of the photosphere, chromosphere, a transition region and the corona. The solar interior, from the inside out, is made up of the core, radiative zone and the convective zone. The sun and the atmosphere of the sun are divided into several zones and layers. (Image credit: NASA/JPL-Caltech) Internal structure and atmosphere of the sun Diagram showing the sun at the center of our solar system (not to scale).

Age of space