The Science Behind NASA's 'Smiling' Sun

This year's Halloween spirit was out of this world. Ahead of the costume and candy-filled celebration, NASA's Solar Dynamics Observatory captured an image of the sun "smiling" – an image that acclaimed cosmologist compared to a "giant space pumpkin." 

The image, which shows a glowing sun with two black holes on top of another crescent-shaped "smile," was captured on October 26. 

"Seen in ultraviolet light, these dark patches on the Sun are known as coronal holes and are regions where fast solar wind gushes out into space," NASA tweeted. 

The adorable image of the sun was certainly a treat, but it came with tricks as well. The coronal hole trio prompted a minor geomagnetic storm watch on Saturday, with NOAA's Space Weather Prediction Center warning that the holes were anticipated to "enhance and disturb the solar wind environment and lead to unsettled conditions." 

Coronal holes, according to NASA, are areas of the sun that appear dark because they are cooler and less dense than the surrounding regions and have open magnetic fields. These characteristics allow "streams of relatively fast solar wind" to escape more easily. The holes can develop at any time and location on the sun and the winds can cause geomagnetic storms, ranked on a scale from G1 (minor) to G5 (extreme), which have the power to disrupt power and other systems on Earth while also impacting spacecraft operations.

Even minor storms can cause "weak power grid fluctuations," according to the center, and impact satellite operations and migratory animals. These storms also cause the northern lights to become more visible further south. 

In the most extreme storm, some grid systems can experience "complete collapse" and an aurora can be seen as far south as Florida and southern Texas. 

The "unsettled conditions" were expected to extend through Wednesday, the center said last week. As of Monday, however, no geomagnetic storms or "significant transient or recurrent solar wind features" are expected. On Sunday, the center said there have been "no geomagnetic storms" in the past week. 

The sun put on a similar Halloween-esque face in 2014, when NASA captured images of the sun looking like an eerie jack-o-lantern. The somewhat spine-tingling glow that was seen coming out of the sun were caused by areas that were emitting more light and energy, NASA said at the time.