All the planets, moons, and smaller things in the solar system are just dust, compared to the star that they orbit; the Sun contains 99.9% of the mass of the solar system. We think of it as our source of light, but it doesn't just emit photons. The solar wind blasts fast-moving electrons, protons, and highly ionized atoms in all directions, a constant stream punctuated by ferocious coronal mass ejections. The solar wind carries with it a magnetic field wound into a tight spiral by the Sun's rotation.
The solar wind pushes outward against the interstellar medium, penning the solar system inside a bubble called the "heliosphere" that's at least 200 AU across. The twin Voyager spacecraft are now probing the heliosphere's edges. Closer to home, a fleet of spacecraft monitors the space weather generated by the Sun, warning us of its effects on Earth, from the benevolent (aurorae) to the potentially disastrous (irradiation of astronauts and damage to communications satellites and power grids). Currently operating solar space observatories include ACE, GGS, WIND, Hinode, PICARD, RHESSI, SOHO, SDO, Solar Monitoring Observatory, and STEREO.
Latest Blog Entries about the Sun, Heliosphere, and Space Weather
Posted by Emily Lakdawalla on 2011/12/05 04:13 CST
A report on a press briefing about Voyager 1 at the Fall 2011 American Geophyisical Union meeting. The spacecraft has entered a new region between our solar system and interstellar space, which scientists are calling the stagnation region.
LADEE ended its mission as planned with a crash into the lunar surface on April 17. Just days prior, it turned its star tracker camera toward the lunar horizon and captured a striking series of images of the lunar sunrise and zodiacal light.
Curiosity has been shooting photos of the Sun as Phobos and Deimos cross its face, and -- as far as I can tell -- captured sunspots as well.
Here's a neat video posted by SungrazerComets (the Twitter identity of the U.S. Naval Research Laboratory's Sungrazing Comets website) this morning. It's an animation of images taken by the Solar and Heliospheric Observatory (SOHO) on May 13 and 14, when Jupiter was passing through solar conjunction
In 2016, The Planetary Society’s LightSail program will take the technology a step further.