It's EVE Cruciform Maneuver Day!

SDO is performing the EVE cruciform calibration manuever today, starting at 1130 UTC (7:30 am ET) and running for about 8 hours. During this maneuver science data may be missing or blurry.

Momentum Management Maneuver #38 Today

SDO will execute momentum management maneuver (MM) #38 today starting at 1930 UTC (3:30 pm ET). The maneuver should take about 30 minutes. During a maneuver SDO science data may be missing or blurred. These maneuvers are needed to keep SDO accurately pointed at the Sun and taking data.

SDO Manuevers and Plans for July through September

SDO will perform the following maneuvers during the next three months. During a maneuver science may be blurry or missing. Other important dates (such as handover and eclipse seasons) are included for your information. Many of the calibration maneuvers were delayed due to the COVID-19 closures.

• July 08, 2020: HMI Roll Maneuver (@ 1500ut)
• July 14, 2020: HGA Handover Season Begins
• July 15, 2020: Delta-H Maneuver #38 (@ 1942ut)
• July 22, 2020: AIA GT/PZT Calibration (@ 1500ut)
• July 29, 2020: EVE Cruciform Calibration
• August 03, 2020: Eclipse Season Begins
• August 12, 2020: Stationkeeping Maneuver #21
• August 17-19, 2020: Solar RFI
• August 27, 2020: End of Eclipse Season
• September 05, 2020: End HGA Handover Season

Momentum Management Maneuver #37 Today

SDO will execute Momentum Management Maneuver #37 today at 1838 UTC (2:38 p.m. ET). From 1830 to 1930 (UTC) science data may be missing or blurred.

Hale’s Polarity Law in Solar Cycle 25

The magnetic field of the Sun has several patterns and follows a few laws. Hale’s Polarity Law is one of those. It says that the leading and trailing magnetic fields in an active region have the opposite direction and the directions flip in the next sunspot cycle.

Here is proof of the flip going into Solar Cycle 25. On the left is an HMI magnetogram from April 3, 2011, during the rise to the maximum of Solar Cycle 24. There are several active regions in the Northern hemisphere of the Sun. The magnetic field going into the Sun is shown as black and the outward field in white. Arrows point to three active regions (AR 11180, 11183, and 11184, right to left arrows) and show that the inward field leads the outward field.

On the right is a magnetogram from April 2, 2020. A high-latitude active region (AR 12759) has the outward field is leading the active region and the inward magnetic field is behind. AR 12759 is at 28 N (the same latitude as Cape Canaveral, FL, SDO’s launch site).

Hale’s Polarity Law is one of the reasons for the confusing names of the solar cycle. People see an 11-year sunspot cycle when they look only at sunspots. The reversal of the leading and trailing fields means that two sunspot cycles are necessary for the Sun to return to the same conditions (the 22-year solar cycle). But we still count Solar Cycles. So Solar Cycle 25 is the 25th sunspot cycle since records the numbering began in 1755.

The high-latitude, oppositely-directed field active region AR 12759 is just the beginning of Solar Cycle 25.The leading field is an outie!

Lunar Transit Last Night!

Yesterday, from 6:00--8:33 pm, the Moon moved between SDO and the Sun. These lunar transits happen a few times each year. Here is the FOT movie of the event, produced last year. The transit covered a maximum of 57% of the Sun.

And here is a 60-hour movie in AIA 171 Å. There are three eclipses of the Sun by the Earth near 0700 UTC on February 22, 23, and 24. The lunar transit starts at 2300 UTC on February 23 and lasts until 0133 UTC on the 24th.

Lunar transits are one interesting feature of life in a geosynchronous orbit.

Station Keeping Maneuver #20 Today

SDO will execute Station Keeping Maneuver #20 today at 2230 UTC (5:30 p.m. ET). From 2200 to 2250 UTC (5:00-5:50 p.m. ET) science data may be missing or blurred. Station-keeping maneuvers are designed to keep SDO’s orbit in the right place when the spacecraft travels through the geostationary belt twice each day.