Large Angle and Spectrometric Coronagraph (LASCO)

FUNCTION: Designed to answer some fundamental questions: How is the corona heated? Where and how is the solar wind accelerated? What causes coronal mass ejections, and what role do they play in the evolutionary development of large-scale coronal patterns?DESCRIPTION: The LASCO and Extreme-ultraviolet Imaging Telescope (EIT) instruments are two of 11 instruments included on the joint NASA/European Space Agency (ESA) SOHO (Solar and Heliospheric Observatory) spacecraft. SOHO was launched on December 2, 1995, at 0808 UTC (0308 e.s.t.) from the Kennedy Space Center, Cape Canaveral, Florida. The spacecraft is located about 1 million miles from Earth, between Earth and the Sun in a halo orbit about the L1 Lagrangian point. This point is where the gravitational and orbital forces are balanced. About 250 images are returned from LASCO and EIT each day, providing unprecedented views of the Sun and its corona, recording the source of major geomagnetic storms.INSTRUMENTATION: The LASCO instrument is a suite of three coronagraphs that image the solar corona from 1.1 to 32 solar radii (about 1/7 of the distance to Earth). It is convenient to measure distances in terms of solar radii. One solar radius is about 700,000 km, 420,000 miles, or 16 arc min. The EIT instrument images the solar disk to 1.5 solar radii in four narrow wavelength intervals from 17.1 to 30.4 nm. These intervals roughly correspond to ionization temperatures of 60,000 K to 3 MK.