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Our Sun

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

Take My Free Online College Introduction to Planetary Science and Astronomy CSUDH Class

Posted by Bruce Betts on 2014/02/05 05:02 CST | 8 comments

Our own Dr. Bruce Betts is once again teaching his Introduction to Planetary Science and Astronomy college course online. Come join him.

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Sungrazing with Lovejoy's Comet

Posted by Jason Davis on 2011/12/06 10:42 CST

Observations of the newly sighted Kreutz sungrazer comet C/2011 W3 (Lovejoy) from the ground and from SOHO (a joint NASA/ESA satellite) and STEREO (NASA's Solar Terrestrial Relations Observatory).

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Spotting Jupiter's Moons...with a Solar Telescope!?

Posted by Emily Lakdawalla on 2011/04/06 12:27 CDT

I was astounded to learn this morning that SOHO can not only see Jupiter, it can actually resolve Jupiter's moons (at least its two outer ones) as points of light separate from their planet!

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Some Details About Transits of Venus

Posted by David Shortt on 2012/05/22 06:02 CDT | 2 comments

The upcoming rare transit of Venus is one step in a long dance among Earth, Venus and the Sun. Transits of Venus follow a peculiar pattern—two transits 8 years apart, then 105.5 years with no transits, then two transits 8 years apart, then 121.5 years with no transits, for a total cycle of 243 years—and thereby hangs a tale.

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Solar storm in progress

Posted by Emily Lakdawalla on 2012/03/07 09:27 CST

Last night the Sun unleashed a large coronal mass ejection in our direction. Here is a compilation of images from SOHO's two LASCO cameras, plus a prediction from the new space weather prediction model that I learned about at the American Geophysical Union in December. The storm will arrive at Earth on March 8.

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