The solar wind is a constant in the solar system, but on Christmas Day 2022, it abruptly and totally disappeared. A NASA spacecraft orbiting Mars noticed the strange occurrence and discovered that the magnetosphere of the Red Planet responded by tripling in size.
As the Sun functions as a massive nuclear fusion power plant, it continuously releases a charged particle stream known as the solar wind. All of the planets are insulated by this, and if it weren’t for the magnetosphere that deflects inbound particles, their atmospheres would be stripped away.
The solar wind varies, but it shocked astronomers last December when it abruptly stopped for a few days. MAVEN, a NASA orbiter examining Mars’ atmosphere, discovered the anomaly when its instruments registered a 100-fold decrease in solar wind density. The magnetosphere and ionosphere of the Red Planet expanded to three times their normal size in the absence of the solar wind’s pressure.
According to Jasper Halekas, the study’s lead author, “When we first saw the data, and how dramatic the drop in the solar wind was, it was almost unbelievable,” “We formed a working group to study the event, and we have found this time period to be rich with incredible findings.”
The ionosphere changed from being magnetized to being unmagnetized, according to MAVEN, and the area near the boundary experienced significantly less electromagnetic activity than usual. The solar wind reappeared about two days later, giving the NASA team a unique window into an atypical set of circumstances.
Halekas stated, “When the solar wind is effectively removed, we are really getting to see how Mars responds.” “It makes for a great outlier study on what Mars would be like if it were orbiting a less ‘windy’ star.”
According to the team, a rare interaction between solar wind waves caused the drop-off. A faster wave passed by a slower one, and as a result, the two waves compressed into one, leaving a less dense area in their wake. Rarely, this phenomenon has been observed; one such instance occurred in 1998 and washed over Earth. However, spacecraft that are as positioned as MAVEN are typically not available to study these phenomena.
