SDO Sees the Moon Transit the Sun. Twice.

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

September Starts with Flare(s)

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

Watching a Sunspot

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

Another Flare

quad-flareDuring a December, 2013, solar flare, three satellites watched a current sheet form. This animation shows four views of the flare from the Solar Dynamics Observatory, the Solar and Terrestrial Relations Observatory, and JAXA’s Hinode. The current sheet is a long, thin structure, especially visible in the views on the left. Those two animations depict light emitted by material with higher temperatures, so they better show the extremely hot current sheet.

A current sheet is a very fast, very flat flow of electrically-charged material, extremely thin compared to its length and width. Current sheets form when two oppositely-aligned magnetic fields come in close contact, creating very high magnetic force.

Image Credits: NASA / JAXA

Lines of Force

magnetic_field_lines_2When we were in school, many of us saw that demonstration about a magnet’s lines of force using iron filings on a piece of paper covering a magnet. This illustration lays a depiction of the Sun’s magnetic fields over an image taken by the Solar Dynamics Observatory. Note how the magnetic fields are densest near the bright spots visible on the Sun’s surface. They are magnetically strong active regions, and many of the field lines link one active region with another.

Image Credit: NASA

A Solar Prominence

An elongated solar prominence’s rising up above the Sun’s surface was captured in this video by the Solar Dynamics Observatory. Prominences, also known as filaments when move over the Sun’s limb, are clouds of solar material suspended above the surface by the solar magnetic field—the magnetism that drives solar events such as flares and coronal mass ejections.These images used to make this video were taken in extreme ultraviolet wavelengths of 3.04 nm. That wavelength invisible to human eyes so it’s coded here as red.

The sun appears to move in the last few seconds of the video. The glitching occurs because SDO was being calibrated as this data was taken.

Video Credit: NASA

Cascading Magnetic Arches

This time lapse video was taken by the Solar Dynamics Observatory using UV light and shows a dark solar filament above the Sun’s surface that became unstable and erupted, generating a cascade of magnetic arches. A small eruption to the upper right of the filament may have been related to its collapse. The arches of solar material glow as they emit light in extreme ultraviolet wavelengths, highlighting the charged particles spinning along the Sun’s magnetic field lines.

Video Credit: NASA

Magnetic Loops on the Sun

Two active regions sprout arches of bundled magnetic loops in this video from the Solar Dynamics Observatory taken on 11 and 12 November, 2015. Charged particles move along the magnetic field, tracing out bright lines as they emit light in extreme ultraviolet light. Around the middle of the video, a small eruption from the active region near the center causes the coils to rise up and become brighter as the magnetic field realigns.


Video Credit: NASA

Coronal Loops

Coronal LoopsThe Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory images the solar atmosphere in 10 wavelengths every 10 seconds. Its data is used to link changes in the surface to interior changes in the Sun.In this image the Sun’s magnetic field can be readily visualized through bright strands called “coronal loops”. Loops are shown here in a blended overlay with the magnetic field measured by SDO’s Helioseismic and Magnetic Imager shown underneath. Blue and yellow represent the opposite polarities of the magnetic field.

Image Credit: NASA

Magnetic Links

In this video constructed of images taken by the Solar Dynamics Observatory from 3 through 6 January, a series of linked loops across the face of the Sun highlight the dynamic magnetic connections generated by several active regions. Active regions have magnetic north and south polarity, and the arcing loops seek the opposite pole to make the connection. These images were made in a wavelength of extreme ultraviolet light.


Image Credit: NASA