Friday, September 28, 2012

Fall 2012 Eclipse Season Ends Tomorrow

The Fall 2012 SDO eclipse season ends tomorrow. Here is a look at the penultimate eclipse in the AIA 1600 bandpass. This wavelength of light is absorbed by the Schumann-Runge continuum of molecular oxygen at an altitude of about 110 km. This creates atomic oxygen, which moves upwards and creates the thermosphere. That atomic oxygen also is ionized by solar EUV to create the ionosphere.
At this wavelength the Sun looks like a ball with a thin, lacy network, bright active regions, and dark sunspots. Many of these features are a little above the visible surface of the Sun. They are held up by the solar magnetic fields. Welcome to the chromosphere, a layer of the solar atmosphere that will be studied by the Iris satellite. The people at LMSAL who built AIA and HMI are building Iris and hope to launch it in January.

Thursday, September 27, 2012

Station-Keeping Maneuver Successful!

Last night at 2250 UTC (6:50 pm ET) SDO performed another station keeping maneuver. These short firings of the thrusters keep SDO within the longitude box that defines its inclined geosynchronous orbit. The timing of the maneuver is chosen to affect as little of the science data feed as possible. This means it is often near dusk or dawn so that the velocity of SDO very nearly in the direction of the thrusters. We off-pointed only 1" (less than the size of the Sun) for this maneuver.
We are nearing the end of the Fall 2012 eclipse season on September 29. A few more partial eclipses and we will be seeing the Sun 24/7 until the Spring 2013 eclipse season!
As with any geosynchronous satellite, our ground station experiences radio interference (RFI) near the equinox when the spacecraft appears to pass close to the Sun in the sky. This is because the Sun is a source of radio noise that can overwhelm the signal we are listening to. This years RFI season has passed without loss of any data.

Wednesday, September 26, 2012

Website is Back, New Sun-Grazing Comet Seen Near Jupiter

The SDO website has returned to service.
A Russian observatory is announcing the discovery of the a new sun-grazing comet, this time out near Jupiter. Comet C/2012 S1 (ISON) will approach close to the Sun in November 2013, possibly as close as 0.012 AU (about 2 Rsun above the surface). It may become visible to the naked eye as well.
Comets become visible because they outgas water and other molecules, which reflect sunlight. The further from the Sun the comet becomes visible the bigger the comet usually is. Let's hope that we can get some nice data from SDO during the perihelion passage of Comet C/2012 S1 (ISON).

Power Outage of SDO Website

The SDO website will be down while a power line is run into the server room at Goddard. It should return to service later this morning.

Wednesday, September 19, 2012

A "Jovial" Transit of Venus

If you lived on Jupiter you would be able to see a transit of Venus tomorrow. It might look something like the one we saw in June. Here is an example in SDO AIA 171, a time-lapse still of the black disk of Venus moving across the Sun. Even though the transit can't be seen from Earth, the Hubble Space Telescope may be able to see the small decrease in sunlight reflected off Jupiter toward Earth during the transit. SDO will help by telling the scientists how the Sun's brightness changes during the transit. Given how quiet the Sun has been of late, that should be pretty easy for us to do. Jupiter is ahead of the Earth in its orbit around the Sun, so the quiet side is rotating to face Jupiter, even as a new active region rotates into the view of the Earth.
First contact is at 0456 UTC, mid-transit is 0953 UTC and 4th contact is 1451 UTC (all September 20 UTC). That means the transit at Jupiter lasts almost 10 hours (compared to about 7.5 hours for the June 2012 Venus transit at Earth).
It's all part of our search for Earth-like planets around other stars. We see a lot of planets in the Kepler data; how can we determine which ones have water and oxygen?

Thursday, September 13, 2012

SDO Image is Number 1 in SpaceShots

It is always nice to see an SDO image as the number 1 in a top 10 list. Fox News selected the "whip" filament as the top image in early September.

Thursday, September 6, 2012

Fall Eclipse Season has Begun

Today was the beginning of the Fall 2012 eclipse season. This image in AIA 171 shows that the Earth covered about half of the Sun this morning at 0700 UTC.
With the SDO geosynchronous orbit comes an eclipse season twice each year. They last for several weeks; this will end on September 26 (just in time for our next maneuver).

Wednesday, September 5, 2012

Images are Once Again Available

The database update at the JSOC has ended and data is once again flowing to the right places.

Tuesday, September 4, 2012

Temporary outage of browse data

The Stanford site is undergoing database maintenance mid-day on September 4. Unfortunately, browse data will not be available during this period.

Time for Prominences and Filaments

When I checked the kiosk movies today I saw that the edge of the Sun is ringed by prominences. And the face of the Sun is littered with filaments. If you check out the kiosk movie in the 304 band, you will an enormous eruption at 2 o'clock, quiescent prominences at 3, 5, and 7 o'clock, another eruption at 8 o'clock, and something interesting at 10 o'clock. With the 15-minute cadence of the kiosk you see flickering on the face as filaments erupt and move into space. A few small C-class flares happened over the weekend, but the prominence and filaments were the real show over the Labor Day weekend.

Saturday, September 1, 2012

Happy Space Weather Day!

Today is the 154th anniversary of the Carrington event. A large flare was observed on the Sun and a magnetic disturbance was seen to happen soon after. It was the largest space weather event ever observed.
To honor this observation, I think we should name September 1 as Space Weather Day!
For the more mathematically inclined, 154 is a sphenic number, a product of three distinct prime numbers (154 = 2 x 7 x 11). Other sphenic numbers are 30 (2 x 3 x 5) and 42 (2 x 3 x 7).