IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
The Birth of an Active Region
Credit: IRIS, LMSAL/NASA, Chad Madsen
This movie comprises seven separate observations of the same region stitched end to end. It features the birth and growth of an active region over a day and a half, a phenomena that IRIS has never before captured. An active region is a place on the Sun where its magnetic field has broken through its surface. The emerging magnetic field heats the plasma around it, causing the active region to be brighter than its surroundings. Furthermore, the field is responsible for many of the dramatic events featured in other IRIS movies, such as flares, jets, and eruptions. The movie starts off with a rather innocuous scene: a typical patch of quiet Sun. Suddenly, a small bright region appears just below the center of the frame: this is the moment the active region is born. The bright region then begins to spread out, creating a small canopy of thin, wispy arches of plasma tied to the emerging magnetic field. This rapid growth is far from peaceful; small, short-lived, violent brightenings pepper the newborn active region as the complicated canopy of magnetic field arches untangles itself and interacts with the existing field above it. As the active region spreads further, the magnetic field consolidates and strengthens, leading to the formation of sunspots where the field halts the convection of hot material upward, producing these cooler, darker regions. At the end of the movie, we have a vast, stormy region teaming with pent up energy it will desperately release in some of the most violent and spectacular feats in the solar system environment.