NASA's Solar Dynamics Observatory caught this picture of the moon (black cricle) passing in front of the sun just as it was emitting a solar flare (left side of sun). (NASA/SDO)
NASA’s Solar Dynamics Observatory (SDO) has been orbiting the Earth and keeping eyes on the sun since its launch in February 2010. Yesterday morning starting at 8:31 a.m. Eastern, the moon passed between the Earth and SDO for about an hour and a half, the longest such transit ever recorded, providing ample time for SDO to snap pictures of the black circle of the moon eclipsing the fiery sun. These transits occur two to three times each year, according to NASA.
In the photos, the moon appears nearly as large as the sun, due to the moon being so much closer to SDO than our star, which is nearly 93 million miles away from Earth. (The farthest the moon ever gets from Earth is about 400,000 miles.) The moon’s edge is so sharp in the photos because it has no atmosphere to distort the sun’s light.
At the same time as the eclipse, the sun decided to put on a show and emit a mid-level flare, which peaked at 11:11 a.m., just as the moon began to pass out of view. Solar flares are bursts of light that happen when sunspots or structures called filaments erupt and release their energy. (MORE: Huge Sun Explosion Captured by NASA Photos)
The flares send waves of charged particles out into space, which, if they reach Earth, can disrupt communications and GPS satellites but won’t harm humans. Yesterday’s flare was also accompanied by a phenomenon called a coronal mass ejection (CME), which sends material from the sun shooting out into space and causes auroras when they reach Earth’s atmosphere.
The current CME isn’t headed directly toward Earth, according to NOAA, but could cause minor geomagnetic storms in the next few days.
First up, the basics. Here's the sun's mass, in pounds: 4,385,214,857,119,400,000,000,000,000,000. That's about 333,000 Earths. An empty sphere the size of the sun could hold about a million Earths. At its surface, the sun is about 10,000 degrees Fahrenheit, which is basically frigid compared to the 27 million degrees at its core. (NASA/SDO/AIA)