Explore – Exhibits – Ahmanson Hall of the Sky – The Active Sun

The Active Sun

When we observe the Sun, we are looking at an active star. We measure its temperature and watch its outer atmosphere to understand how it works. The visible surface of the Sun appears to be in full boil. Often, we can see sunspots through the turbulence. These magnetic storms appear dark because they’re cooler than the surrounding areas.

Occasionally, solar flares and coronal mass ejections send glowing gas and charged particles through the Sun’s million-degree corona. These form the solar wind that streams out past the planets.

The Active Sun: Time-lapse movies of the full-disc Sun show the constant activity of our local star. The images are from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Bright and dark areas on the Sun reflect differences in temperature. As the Sun turns, you can see eruptions and flares across the Sun’s surface.

Eruptions and Flares: The Sun is in a period of near-maximum activity in this time-lapse movie taken from October 21 – November 6, 2003. The images are from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. When an eruption occurs on the side of the Sun facing the Earth, the blast of radiation affects the sensors of the spacecraft, as well as other satellites, communications, and electrical systems on Earth. Activity on the Sun is often measured in 11-year cycles, with the period of maximum activity characterized by massive flares and eruptions.

Prominences: Time-lapse movie of four days (February 16-19, 2003) of the edge of the Sun from NASA’s Transition Region and Coronal Explorer (TRACE) spacecraft. The rising and falling dark areas are prominences, large streams of gas and plasma cooler than the surrounding surface. They follow the Sun’s magnetic field lines until the lines collapse and the material and energy is ejected into space.

Space Weather: The Sun churns with activity in this time-lapse movie taken from October 18 – November 7, 2003. The images are from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Eruptions from the Sun send massive amounts of energy, radiation, and plasma streaming out into space. When an eruption occurs on the side of the Sun facing the Earth, the resulting radiation can affect profoundly satellites, communications, and other electrical system on Earth.

The Sun’s Edge: Time-lapse movie of two days (March 22-23, 2001) of the edge of the Sun from NASA’s Transition Region and Coronal Explorer (TRACE) spacecraft. Bright plasma loops trace magnetic irregularities across the surface of the Sun and into space. The bright areas are those seen in ultraviolet light, and they are produced by plasma heated to nearly four million degrees Fahrenheit.

The Sun’s Gravity: Time-lapse movies show comets both plunging into and passing by the Sun. The images are from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Comets go around the Sun in large, elliptical orbits. Over time, the Sun’s immense gravity can change a comet’s orbit so that it comes too close to the Sun to escape. Because of its unique and continuous view of the Sun, SOHO has discovered more comets than all observers in history combined.

Sunspots: Time-lapse movies of the Sun’s rotating surface show full-disc and close-up views of sunspots. The images are from the ESA/NASA spacecraft and ground-based telescopes. Sunspots are dark, planet-size regions cooler than the surrounding solar surface. They occur because of the pressure of the surrounding magnetic field.