Why is it in the News?

Recently, NASA's Soho mission, which is tasked with observing the Sun, has captured its 5000th comet as it dives around the star in our Solar System.

About Solar and Heliospheric Observatory (SOHO):

• SOHO was built as a general solar observatory, with twelve suites of scientific instruments to track all of these properties of the Sun.
• During its operations, it has provided important insights, including:
  • Details about the interior of the Sun,
  • What sunspots look like beneath the surface,
  • Measurements of the speed of the solar wind,
  • The charged particles that escape from the corona,
  • Mapping the magnetic field behavior over the Sun’s surface; and
  • Revealing new phenomena such as “solar tornadoes”.
• Built in Europe, SOHO is operated jointly by ESA and NASA, with contributions from a large number of scientists, engineers, and other staff around the world.
• The spacecraft was launched in 1995 with a planned two-year mission.
• Its work was successful enough to justify keeping the observatory going, and it’s still operating more than 20 years later.
• The probe orbits the Sun at a place where the gravity of the Sun and Earth balance each other out, known as the first Lagrange point (L1).
• Center for Astrophysics (CfA) scientists and engineers provided SOHO’s Ultraviolet Coronagraph Spectrometer (UVCS), which operated until 2013 and measured the ultraviolet spectrum of the hot solar atmosphere.
  • UVCS provided the insight that the corona is too hot to be produced by ordinary thermal transfer, where particles collide and pass energy to each other.
  • Instead, the corona and solar wind must be accelerated by the magnetic field interactions in some way.
• Other SOHO instruments measure the speed and composition of the solar wind; the seismic waves that travel across the Sun’s surface; the fluctuations in the temperature, composition, and density of different parts of the corona; and the motion of matter upward from the Sun’s interior to its surface.