The Sun’s Far Side as Seen via Martian Observations and GONG Helioseismic Mapping

Solar activity is now in the declining phase of Solar Cycle 25, leading to a marked reduction in both the number of active regions and the frequency of high‑energy events. Front‑side active regions continue to be monitored routinely from ground‑ and space‑based observatories, but the far side lacks continuous direct coverage. NASA’s STEREO spacecraft and ESA’s Solar Orbiter provide intermittent far‑side observations that have been essential for validating helioseismic techniques used to infer active regions on the hidden hemisphere. However, because the visibility of the far side depends on each spacecraft’s orbital position, none of these assets provide full‑hemisphere far‑side coverage at all times. For more information, please see an earlier post,

https://gongnisp.blogspot.com/2025/12/why-active-regions-appeared-displaced.html

Recent observations from NASA's Perseverance rover on Mars — currently positioned on the far side of the Sun relative to Earth —provide a valuable additional vantage point for viewing the Sun’s hidden hemisphere. In the image shown here, we compare the far‑side active regions inferred from GONG helioseismic mapping with those detected in the recently published Mars‑based observations reported by Spaceweather.com.

Martian observation (right bottom panel of the accompanied image) indicates that four active regions seen on March 6 in the northern hemisphere (left panel) remain on the solar disk, and these same regions are also captured in the GONG helioseismic maps (right top panel). One region highlighted in the GONG maps (marked with a red circle) does not appear in the Martian observations because of its position relative to Mars’s viewing geometry. The line marking this location shows clearly that the region lies outside Mars’s field of view. These differences arise primarily from the distinct image geometries and viewing angles of the two observing platforms.

M-class flare and prominence activity

A major M2.8 X-class flare occurred today (16 March 2026) in active region 14392. The flare started at about 12:00 UT and peaked at 12:15 UT. Flare and an activation and eruption of small filament from nearby active region was observed by several GONG stations. See video of event as observed in the hydrogen H-alpha spectral line by GONG/Cerro Tololo, Chile. Unrelated to this event, a large solar prominence in East-South limb showed some interesting flows. Flaring region is shown at 2 minute cadence time lapse, and the prominence is at 3 minute cadence. Videos cover about 5 hours for flare (11:34 UT- 16:36 UT) and 6 hours for prominence (11:34 UT- 17:35 UT). Full disk images for these events can be accessed via GONG web site at  https://gong.nso.edu/.

 

GONG status for week of March 8-14 2026

 Here is a brief status of GING operations for week of March 8-14, 2026:

Most Instruments Operational: Instruments at Learmonth, Udaipur, El Teide, Cerro Tololo, and Big Bear were generally operational, though with varying sky conditions.

Instrument Down Time: GONG TC and TE instruments were down for testing. Access road to Mauna Loa Observatory is  now scheduled to be completed on March 25, 2026. 

Maintenance: A maintenance report for the El Teide site on March 11 noted that the anemometer was connected, but the emergency light inside the shelter had a bad battery.

Scheduled Scans: DRIFT Scans were performed at the Big Bear site on March 8 and March 14.

Community support: GONG observations were used to support the NASA's Parker Solar Probe’s 27th encounter, with perihelion that occurred on March 11 at 18:17 UT. Maps of predicted magnetic connectivity  based on GONG observations can be found at https://whpi.hao.ucar.edu/whpi_campaign-psp27p.php 

GONG/TD status

GONG/Teide (Canary Islands) has been down for several days (2-4 March 2026). They had very bad weather with temperatures bellow 0º and very high humidity. Probably ice at formed on the turret. Local support team investigates.

A day without sunspots

Observations from GONG taken on 22 February 2026 show no sunspot (see upper-left image showing the Sun in a broadband wavelength range). Areas of brighter plages indicate the presence of magnetic field on the Sun, but the field is not strong enough to form sunspots or even pores. Image on upper-right is a map of magnetic fields (magnetogram) corresponding to the same time as the "white light" image. There dark/white colors correspond to magnetic field of negative/positive polarity.  The magnetic fields are organized in patterns of positive-negative polarity typical for decaying active regions. The conditions with no sunspots are usually observed during the minimum of 11-year solar cycle, although currently, the sun is in the middle of a declining phase of solar cycle 25 (see last plot taken from https://www.swpc.noaa.gov/products/solar-cycle-progression). 

 

One day of a large solar prominence

 On 21 February 2026, a large solar prominence was observed on East-South limb. This video shows the change in filament appearance over 24 hour period. Video stars from GONG/Learmonth (Australia) at 00:00:42 UT. Then it switches to GONG/Cerro Tololo (Chile), and at the end, it goes
back to GONG/Learmonth. The video ends on 22 February 2026 at 1:48:42 UT.

Wildlife near GONG station in Udaipur

Apparently, GONG is recognized as an important asset not only by solar scientists. Image on the left shows a curious puma poking out her head above bushes outside GONG fenced area. On the right, puma walks toward GONG area crossing observatory road.