SECCHI team obtains images of the solar wind at Earth

Dec 07, 2007

Using the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instruments on board NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft, a consortium of scientists has seen, for the first time, large waves of solar material sweeping past Earth.

The SECCHI team has obtained images of the density enhancements whose prior existence was known only from point measurements by in situ spacecraft. The team’s results will be discussed during an invited talk by Dr. Neil Sheeley of the Naval Research Laboratory (NRL) at the fall meeting of the American Geophysical Union in San Francisco, CA, in December. The scientific paper is scheduled for publication in the March 1, 2008 issue of the Astrophysical Journal.

During relatively quiet solar conditions throughout the spring and summer of 2007, the SECCHI Heliospheric Imager HI-2 telescope on the STEREO B solar-orbiting spacecraft observed a succession of wavefronts sweeping past Earth. The scientists have compared these white-light images with in situ plasma and magnetic feld measurements obtained by near-Earth spacecraft, and found a perfect association between the occurrence of these waves and the arrival of high-density regions that rotate with the Sun. These compression regions are believed to form as high-speed wind from dark areas of the solar corona known as coronal holes run into the low-speed wind in front of it.

Currently, the researchers are tracking HI-2 waves backward toward the Sun to see exactly how they originate. Preliminary results suggest that the waves begin as blobs of material that are shed continuously from coronal streamers.

The STEREO twin spacecraft were launched on October 25, 2006 with the objective of obtaining stereoscopic observations of the Sun from a near-Earth orbit. After some initial maneuvers, which included a gravitational assist from the moon, the two spacecraft achieved their orbits with one spacecraft (A) located slightly closer to the Sun and gradually moving ahead of Earth and the other spacecraft (B) located slightly farther from the Sun and gradually falling behind. The angular distance between the A and B spacecraft increases at a rate of approximately 45 degrees per year and was about 26 degrees in early September 2007.

Each spacecraft is equipped with a suite of Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instruments. In addition to an extreme ultraviolet imager (EUVI), there are two coronagraphs (COR1 and COR2) and two heliospheric imagers (HI-1 and HI-2) pointing 13 degrees and 53 degrees off to the side.

Source: Naval Research Laboratory

Explore further: France raises heat on decision for next Ariane rocket

add to favorites email to friend print save as pdf

Related Stories

Scientists 'see' flux rope formation for the first time

Apr 03, 2013

(Phys.org) —Naval Research Laboratory scientists have observed, for the very first time, the formation of solar flux ropes, which are a type of solar magnetic field. Models of flux ropes have been drawn ...

NASA’s STEREO spots a new nova

May 01, 2012

While on duty observing the Sun from its position in solar orbit, NASA’s STEREO-B spacecraft captured the sudden appearance of a distant bright object. This flare-up turned out to be a nova — designated ...

STEREO sees complete far side of the Sun

Jun 14, 2011

(PhysOrg.com) -- The far side unveiled! This is the first complete image of the solar far side, the half of the sun invisible from Earth. Captured on June 1, 2011, the composite image was assembled from NASA's ...

STEREO Reveals the Anatomy of a Solar Storm in 3D

Apr 28, 2009

(PhysOrg.com) -- Observations from NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft have allowed scientists to reveal for the first time the speed, trajectory, and three-dimensional shape of solar explosions ...

Recommended for you

Miranda: An icy moon deformed by tidal heating

6 hours ago

Miranda, a small, icy moon of Uranus, is one of the most visually striking and enigmatic bodies in the solar system. Despite its relatively small size, Miranda appears to have experienced an episode of intense ...

The latest observations of interstellar particles

12 hours ago

With all the news about Voyager 1 leaving the heliosphere and entering interstellar space you might think that the probe is the first spacecraft to detect interstellar particles. That isn't entirely true, ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

earls
not rated yet Dec 07, 2007
Nice. I'd like to see their images.