Solar News Highlights from 2002

11/10/02 Solar Activity : The Sun was relatively quiet for much of the week, and there was a period of about 2 days when activity was extremely low, allowing RHESSI to work with the shutters out for long periods. There were only 2 M-class flares before Monday, and 63 C-class flares (17 above C5, 6 above C7). Fortunately, RHESSI managed to catch the entire rise phase of the M4.6 flare on 9 Nov 2002 (15-minute rise period, 28-minute duration), and the entire M2.4 flare on 10 Nov 2002 (17-minute rise period, 31-minute duration).

11/10/02 SpaceWeather News:
AURORA WATCH: On Nov. 9th, an M4-class explosion near sunspot 180 hurled a lopsided coronal mass ejection toward Earth. Sky watchers should be alert for auroras on Nov. 11th or 12th when the cloud sweeps past our planet. (Courtesy

10/31/02 RHESSI Update:

We are pleased to report that as of October 31, 2002, RHESSI has 
achieved its Minimum Science Requirements:

1. Perform hard X-ray (greater than 20 keV) imaging spectroscopy of solar 
flares with better than 4 arcsecond spatial resolution and better than 
3 keV energy resolution.

2. Perform high resolution (better than 3 keV FWHM at l MeV) spectroscopy 
of gamma-ray lines in solar flares.

3. Obtain observations of at least a hundred hard X-ray flares and 
ten gamma-ray (greater than 300 keV) flares.
RHESSI has performed imaging spectroscopy of hard X-ray flares from 
3 keV upward, with 2.3 arcsec resolution, and ~1 keV energy resolution. 
It has obtained high resolution spectra of gamma-ray lines in the 23 
July 2002 flare. On October 31, 2002, it detected its tenth gamma-ray 
(>300 keV) flare. It has also detected over one thousand hard X-ray 
(>25 keV) flares. 

All systems are operating nominally, and we are looking forward to 
eventually achieving the Baseline Science Requirements.

Best regards,
Bob Lin, Brian Dennis, and the RHESSI team


August 2002 RHESSI in the News:
In the August 2002 Issue of Astronomy magazine there was a brief news article about RHESSI: "New Probe of the Sun," by Richard Talcott. Click Here to read the article. Reproduced by permission. Copyright 2002 Astronomy magazine, Kalmbach Publishing Company.

07/28/02 SpaceWeather News:
The Boulder sunspot number reached its highest value in more than a year this weekend;the sun is peppered with spots. On Friday, an explosion near one of them--giant sunspot 39--hurled a coronal mass ejection (CME) into space.  Although the CME was not squarely Earth-directed, some of the cloud is heading our way. It could sweep past Earth as early as Sunday, July 28th, and trigger geomagnetic activity. Sky watchers should be alert for auroras after nightfall.

07/19/02 SpaceWeather News:
Sunspot 30 remains impressive. It stretches 15 Earth diameters from end to end. A second spot (active region 36) has grown nearly as large in recent days. You can see both--but NEVER STARE DIRECTLY AT THE SUN. 

07/16/02 SpaceWeather News:
A remarkable sunspot is crossing the face of the Sun. The large active region stretches 15 Earth-diameters from end-to-end and poses a threat for powerful flares. Indeed, on July 15th, twisted magnetic fields above the spot erupted. The explosion sparked an X-class solar flare and hurled a coronal mass ejection into space. As a result, sky watchers on Earth might spot auroras on Tuesday or Wednesday night.

06/09/02 SpaceWeather News:
SOLAR BLAST: The ESA/NASA Solar and Heliospheric Observatory recorded an unusually beautiful eruption on the Sun today. The giant "prominence" was bigger than 50 planet Earths from end to end. Visit and see for yourself.
Also, DON'T FORGET THE SOLAR ECLIPSE! Across much of North America on Monday, June 10th, the setting Sun will become a strange-looking crescent when the Moon glides in front of our star. Follow the links at for more information, including eclipse-safe observing tips.
WARNING: Never stare directly at the Sun. And never, ever look at the Sun through an unfiltered telescope. Even during an eclipse the Sun can damage your eyes.

06/07/02 RHESSI in the News:
New York Times repoter John Noble Wilford has written an article about some of the latest findings from RHESSI: Close-Up Views of Sun Give Astronomers More to Think About (Free Registration is Required to view the article).

04/21/02 SpaceWeather News:
A BIG SOLAR BLAST: An explosion on the Sun today sparked a powerful X-class solar flare and hurled a coronal mass ejection (CME) into space.
Although the CME was not squarely Earth-directed, the expanding cloud will likely deliver a glancing blow to Earth's magnetosphere on April 22nd or 23rd.  Sky watchers should remain alert for renewed geomagnetic activity and auroras.

04/01/02Spaceflight Now on line spaceflight news.

02/26/02 First Images of RHESSI
No smoke without a fire! The RHESSI satellite observed the ‘fire’ of a solar flare for the first time, whereas the ‘smoke’ in the form of coronal mass ejections is well-known. The red-yellow spot marks the fire that brightened up on the Sun on February 26, 10.26 GMT for a minute. It originated from a gas having a temperature of 200 million degrees and a diameter a third of Earth's. It marks the place where thirty thousand times the European electricity consumption of the year 2001 was released. RHESSI Movie Clip
A sequence of images like the one above is also available in movie form. The high-energy radiation appears only briefly, during the phase of actual energy release.

02/21/02 Space Weather News - movie 1 - movie 2
Solar activity intensified on Feb. 20th and 21st when sunspot magnetic fields erupted several times, producing a series of M-class solar flares.
At least one of the eruptions also hurled a coronal mass ejection (CME) toward our planet. Sky watchers at high latitudes -- e.g., northern Europe, Canada, and across the northern tier of US states -- should be alert for Northern Lights late Friday (Feb 22) or Saturday (Feb 23) when the CME will likely sweep past Earth.

02/06/02The Biggest Explosions in the Solar System-
NASA's RHESSI spacecraft aims to unravel an explosive mystery: the origin of solar flares.

02/05/02 "Sun Cranks our Rare Cookie Cutter Flares" from GSFC Top Story.

02/05/02 RHESSI Launch Day-
New UC Berkeley/NASA x-ray spacecraft heads for the sun after Feb. 5 launch.

02/05/02 Live Video from Cape Canaveral Pegasus Launch

02/05/02 RHESSI participation atNASA Connect's   Having a Solar Blast program for educators. Starts airing: Thursday, March 28, 2002, 11 am ET. The associated activity guide  will be helpful in completing the lesson

01/18/02 "Resurgent Sun" from Science@ NASA

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