On 9 and 10 September, 2018, the Solar Dynamics Observatory, SDO, saw two lunar transits as the Moon passed in front of the Sun. A transit happens when one celestial body passes between another and an observer. This first lunar transit lasted one hour, from 2030 to 2130 UTC and covered 92 percent of the Sun. The second transit happened several hours later, 0152 until 0241 UTC and only obscured 34 percent of the Sun at its peak.
From SDO’s perspective, the Moon seems to move in one direction and then double back. It appears to do so because the spacecraft’s orbit catches up and passes the Moon during the first transit.
Image Credits: NASA
The Solar Dynamics Observatory satellite keeps continuous watch on the Sun. It’s spotted several flares so far this month. The X9.3 flare was the strongest flare yet during the current solar cycle, the roughly 11-year-cycle during which the Sun’s activity waxes and wanes. The current cycle began in December, 2008, and is now decreasing in intensity and heading toward a solar minimum.
Video Credit: NASA
Here’s NASA’s description of the video—An active region on the sun — an area of intense and complex magnetic fields — has rotated into view on the sun and seems to be growing rather quickly in this video captured by NASA’s Solar Dynamics Observatory between July 5-11, 2017. Such sunspots are a common occurrence on the sun, but are less frequent as we head toward solar minimum, which is the period of low solar activity during its regular approximately 11-year cycle. This sunspot is the first to appear after the sun was spotless for two days, and it is the only sunspot group at this moment. Like freckles on the face of the sun, they appear to be small features, but size is relative: The dark core of this sunspot is actually larger than Earth.
Video Credit: NASA
This video contrasts the appearance of the Sun as viewed in UV by the Solar Dynamics Observatory satellite and in millimetre wavelenghts ESO Alma radio telescope array.
Video Credit: ESO / NASA