20 February 2024 - Mission Day: 10308 - DOY: 051
Pick of The Week

Mah Afroz "Moon Illuminator" (October 10, 2023)

This image is a combination of science and art. It was shortlisted in the Royal Observatory Greenwich Astronomy Photographer of the Year competition, the world's largest astrophotography competition. The image has been published in the Astrophotographers of the Year book and is installed in the Royal Observatory Greenwich museum.

The images and text for this Pick of the Week were provided by the artist.

Hi-res TIFF [162M]

Credit: Hassan Hatami.

The image is a combination of data from SOHO's LASCO C2 instrument and SDO's AIA instrument. LASCO C2 shows us the solar corona in white light, while AIA shows the active region of the Sun in the extreme ultraviolet spectrum.

In the active region observed in the extreme ultraviolet, we can see bright spots on the solar disk in green, blue, and red colors, which correspond to the solar spots. Although solar spots are cooler and darker in the photosphere (about 4000 degrees), they appear brighter and hotter in higher altitudes in the active region (up to about 1 million degrees). Given the high number of these spots (solar spots), it can be concluded that the Sun is in its maximum activity phase. Additionally, the shape of the solar corona is more uniform during the maximum activity phase, meaning that the solar corona is not stretched at the equator and is not weak at the poles.

An enormous CME in the northern part of the solar disk in this image shows that the Sun is highly active. The Sun has various layers and activities that are related to each other. If different solar phenomena that are related to each other are observed together, we can better understand the solar activities and physics. The image in the 193 angstrom band shows the magnetic active region that is the source of solar activities. The image in the 211 angstrom band shows the coronal holes that are important sources of solar wind. The image in the 171 angstrom band shows the coronal loops on the solar disk and around the Sun that are stretched in the solar corona and affect the solar corona. The LASCO C2 image shows the solar corona and CMEs that are well visible in the solar corona due to the created active magnetic fields.

Therefore, CMEs and their sources can be observed together in this image. CMEs that we see in this image are very important because they are important sources of solar wind that have serious effects on space weather, especially on Earth's electronic, communication, and space technologies. Polar auroras are just one of the effects of these phenomena. It is very beautiful that we can see the source of Earth's polar auroras with the same appearance as the polar auroras in this image.

The raw data of these observations are not clearly visible and colorful at first. The images are gray, and even most of the image is a black screen with nothing visible. First, we process these images to extract their details, and then we give them artificial colors. For example, we call a wavelength of about 400 nanometers blue, but 171 angstroms is close to soft X-rays, so it cannot have any color, including blue. Artificial colors are used to provide better visual separation and enhance understanding. Space telescopes such as Hubble, James Webb, and Chandra X-ray also use this method for their images.

Dedication. In loving memory: This image is dedicated and carries the name of the artist's sister, Mah Afroz who recently passed away. Her name, means Moon Illuminator in Farsi which means the Sun.


SOHO began its Weekly Pick several years ago after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display. Today, we use this area as 'Solar Picks' to highlight stories, events or activities but not as often as every week.


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Last modification: July 27, 2020

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