NATIONAL GEOGRAPHIC'S SPACE PICTURES THIS WEEK LXIV

Space Pictures This Week: Supermoon, Green Sun
By Andrew Fazekas, National Geographic News, 28 June 2013.

A solar storm rages, smoke billows over Colorado, and the Milky Way resembles a cosmic rainbow in this week's best space pictures.

1. Supermoon Over D.C.

The beauty of Earth's closest companion was on full display as the largest and brightest full moon of the year rose above the Washington Monument in Washington, D.C., on June 23. (See supermoon pictures submitted to National Geographic's Your Shot.)

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 kilometres). That's a bit closer than the typical 238,885-mile (384,400-kilometre) distance.

In 2011, the so-called supermoon was the closest it's been in two decades - only 221,565 miles (356,575 kilometres) from Earth.

2. Green Lantern

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.

3. Cosmic Rainbow

Photograph by Wally Pacholka, TWAN

The Milky Way shimmers like a cosmic rainbow over Utah's Capitol Reef National Park in mid-June.

City dwellers worldwide rarely such starry night skies due to light pollution. (Related: "Best Night-Sky Pictures of 2013 Named.")

4. Cratered

Mercury's crater-filled surface is seen in a June 9 image taken by NASA's orbiting MESSENGER probe from 957 miles (540 kilometres) above the scorched planet.

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.

5. Smoke Trail

Smoke from a giant forest fire in Colorado billows in a striking snapshot taken by astronauts aboard the International Space Station on June 19.

Earth-observing satellites indicate that smoke plumes rose as high as 8.4 miles (13.5 kilometres) into the atmosphere. Thanks to favourable winds, the smoke crossed the eastern part of North America and the Atlantic Ocean, reaching European airspace by June 24.

6. Moon Trio

Photograph by Tamas Ladanyi, TWAN

A trio of spooky supermoons appear to magically rise in concert near Lake Balaton, Hungary, in this composite image taken over the course of a few minutes on the morning of June 23. (Related: "Supermoon Pictures: Best Shots of Year's Biggest Full Moon.")

The orange-red colour can occur when the moon rises or sets, and is caused by moonlight refracting off particles of dust and pollution in Earth's atmosphere.

The next supermoon, which will occur on August 10, 2014, should appear similar to this year's sky show, since it will only be 3.1 miles (5 kilometres) closer to Earth.

[Source: National Geographic News. Edited.]