Tuesday, January 12, 2021

Tomorrow is the First SDO Lunar Transit of 2021

January 13, 2021, will see the Moon pass across the face of the Sun between 0556 and 0625 UTC (00:56 and 1:25 am ET). Here's a movie of the transit from the SDO Flight Operations Team.

This transit occurs while SDO is near the midnight sector of its orbit. That means the motions of the Moon and SDO combine to make this a short transit, lasting only about 30 minutes.


Tuesday, January 5, 2021

Winter Calibration Maneuvers, January 6, 2021

SDO will execute two calibration maneuvers on January 6, 2021. The EVE Field of View (FOV) maneuver will begin at 1315 UTC (8:15 am ET). The HMI/AIA Flatfield maneuver will begin at 1630 UTC (11:30 am ET). During a calibration manuever the SDO science data may be missing or blurred.

Saturday, January 2, 2021

It's Perihelion Day!

Today at 8:50 am ET (1350 UTC) the distance between the Earth and Sun was the smallest it will be this year (perihelion). On July 4, 2020, we were the furthest from the Sun (aphelion). Here is a picture comparing the Sun as seen by HMI on those two days.

The left half shows what the Sun looked last July. The right half is an image from today. The Sun appears a little larger today because of our elliptical orbit around the Sun. This difference also means the telescopes on SDO were designed to fit the Sun at perihelion into the images. I made this from the images on the SDO website. You can make one yourself using the other wavelengths available there.

For every minimum distance of an orbit there is also a maximum distance. For the Earth and Sun this is called aphelion and will next occur on July 5, 2021 6:27 pm ET (2200 UTC).

Friday, January 1, 2021

Welcome to 2021!

SDO was recently told we were renewed for another three years of operations. This will take us well into the rising phase of Solar Cycle 25. I would like to thank all of the people who helped write the Senior Review proposal to keep SDO operating.

Here is a excellent example of the beginning of Solar Cycle 25. This AIA 193 Å movie shows a solar disk with coronal holes, filaments, and a lovely coronal cavity above the limb at 7 o'clock. You can see the filament as the dark lines betwee the cavity and the surface. We should see more cavitites as the polar crown filament continues to form.

Have a prosperous 2021!