Known popularly as a supermoon—or perigee full moon—this phenomenon occurs when the moon reaches its closest distance to our planet while coinciding with a full phase.
Because the moon's orbit is elliptical, there are certain times the moon can be closer (at perigee) or farther (apogee) from our planet, making its apparent diameter appear larger and brighter or smaller and fainter than usual. (Read the full story of this year's supermoon.)
For this year's closest perigee, the moon appeared 8 percent larger and 17 percent brighter than usual, while approaching our planet at a distance of 221,823 miles (356,991 kilometers). That's a bit closer than the typical 238,885-mile (384,400-kilometer) distance.
In 2011, the so-called supermoon was the closest it's been in two decades—only 221,565 miles (356,575 kilometers) from Earth.
Photograph courtesy Bill Ingalls, NASA
A giant bubble of charged particles explodes off the green-tinted surface of the sun, as seen in extreme ultraviolet light on June 18.
One of NASA's twin STEREO (Solar TErrestrial RElations Observatory) spacecrafts captured the moment of eruption of this storm—called a coronal mass ejection (CME)—on the side of the sun not visible from Earth.
Launched in 2006, one of two identical sun-monitoring observatories, STEREO Behind, has been keeping a constant eye on solar activities like sunspots, flares, and CMEs that may pop up on the sun's so-called backside. (Also see "Solar Flare: What If Biggest Known Sun Storm Hit Today?")
STEREO has helped to create more accurate space-weather forecasts by mapping out the violent solar eruptions, which can hit Earth's magnetic field and disrupt satellites and power grids.
The stark shadow line visible above, known as the terminator, is what divides night from day on Mercury. The sun only returns to the same spot in the sky—known as a solar day—on the planet once every 176 Earth days.
Earth-observing satellites indicate that smoke plumes rose as high as 8.4 miles (13.5 kilometers) into the atmosphere. Thanks to favorable winds, the smoke crossed the eastern part of North America and the Atlantic Ocean, reaching European airspace by June 24.