Universe Today

Here are some cool Aurora Borealis pictures. Auroras happen when particles in the solar wind collide with the Earth's magnetic field and become ionized in the high atmosphere. We see a bright light show from down here on the surface of the Earth. It works best in the polar regions, like Alaska.

Aurora and Orion

This is a picture of the Aurora Borealis rising up from the atmosphere of the Earth. You can see the constellation of Orion in the background. This picture was taken by astronauts on board the space shuttle Endeavour as part of mission STS-59.

Aurora Borealis

Here's another picture of the Aurora Borealis taken from orbit. This time it was captured by astronauts on board NASA's Skylab space station back in the 1970s.

Aurora Borealis or northern lights

This is a picture of a beautiful green aurora above the Manicouagan Impact Crater in Quebec. This photo was taken Donald R. Pettit, and astronaut on board the International Space Station as part of Expedition Six.

Aurora Borealis by Expedition 13

Just look at the incredible blues and greens in this picture of the Aurora Borealis captured by astronauts on board ISS as part of Expedition 13.

Glowing Green Beauty of the Aurora Borealis

Here's another picture of the aurora, this time taken by astronauts on board the space shuttle Endeavour as it was docked with the space station.

We've written many pictures about the Aurora Borealis for Universe Today. Here's a story about some Aurora Borealis pictures taken from aircraft, and here's an aurora seen from Mars.

If you'd like more info on auroras, check out NASA's World Book on auroras, and here's a link to some amazing Aurora Borealis pictures taken from Alaska.

We've also recorded an episode of Astronomy Cast all about Auroras. Listen here, Episode 163: Auroras.

Filed under: Astronomy | Comments Off

Colliding auroras photographed by THEMIS all-sky imagers (ASIs) on Feb. 29, 2008. Credit: Toshi Nishimura/UCLA

Scientists recently discovered something about auroras they never knew before. "Our jaws dropped when we saw the movies for the first time," said Larry Lyons of the University of California-Los Angeles,(UCLA) describing how sometimes, vast curtains of aurora borealis collide, producing spectacular outbursts of light. "These outbursts are telling us something very fundamental about the nature of auroras." These collisions can be so large, that isolated observers on Earth — with limited fields of view — have never noticed them before. It took a network of sensitive cameras spread across thousands of miles to get the big picture.
Read more…

Filed under: Missions, Observing | Comments Off

Aurora Australis over the elevated station at Amundsen-Scott South Pole Station, Antarctica. Credit: Calee Allen, National Science Foundation

Like its northern sibling, the aurora australis is strongest in an oval centered on the south magnetic pole. This is because they are the result of collisions between energetic electrons (sometimes also protons) and atoms and molecules in the upper atmosphere … and the electrons get their high energies by being accelerated by solar wind magnetic fields and the Earth's magnetic field (the motions are complicated, but essentially the electrons spiral around the Earth's magnetic field lines and 'touch down' near to where those lines become vertical).

So by far the best place to see aurorae in the southern hemisphere is Antarctica! Oh, and at night too. When the solar cycle is near its maximum, aurora australis are sometimes visible in New Zealand (especially the South Island), southern Australia (especially Tasmania), and southern Chile and Argentina (sometimes in South Africa too).

About the colors: the physics is similar to what make a flame orange-yellow when salt is added to it (i.e. specific atomic transitions in sodium atoms); green and red come from atomic oxygen; nitrogen ions and molecules make some pinkish-reds and blue-violet; and so on.

How high are aurorae? Typically 100 to 300 km (this is where green is usually seen, with red at the top), but sometimes as high as 500 km, and as low as 80 km (this requires particularly energetic particles, to penetrate so deep; if you see purple, the aurora is likely to be this low).

There's a good aurora FAQ at this University of Alaska Fairbanks' Geophysical Institute site (though it, naturally, concentrates on the borealis!).

Aurorae on other planets? Well, as there are strong magnetic fields plus (not so strong) solar wind plus (really deep) atmosphere on Jupiter and Saturn, they have spectacular aurorae, in rings around their magnetic poles (which are closer to their rotation poles than Earth's are). Aurorae have also been imaged on Venus, Mars, Uranus, Neptune, and even Io (atmosphere? solar wind? magnetic fields? sure, but very different than on planets).

Some Universe Today stories on aurorae: Aurora Australis at the South Pole, Aurora Reports from Around the World, Northern & Southern Aurorae Are Siblings, But Not Twins, Chandra Looks at the Earth's Aurora, First Aurora Seen on Mars, and Saturn's "Dualing" Aurorae.

Filed under: Astronomy | Comments Off

Aurora from 2002 in Poker Flats, Alaska. Credit: Dr. Scott Bounds

Aurora australis – southern lights – is the corresponding southern hemisphere phenomenon.

Seeing a bright auroral display may be on your list of 'things to see before I die'! Yep, they are nature's light show par excellence.

Aurora borealis occur in the Earth's ionosphere, and result from collisions between energetic electrons (sometimes also protons, and even heavier charged particles) and atoms and molecules in the upper atmosphere. The ultimate origin of the energy which powers the aurora borealis is the Sun – via the solar wind – and the Earth's magnetic field. Interactions between the solar wind (which carries its own tangled magnetic fields) and the Earth's magnetic field may cause electrons (and other particles) to be trapped and accelerated; those particles which do not escape 'downstream' to the magnetic tail 'touch down' in the atmosphere, close to the north magnetic pole.

The different colors come from different atoms or ions; green and red from atomic oxygen, nitrogen ions and molecules make some pinkish-reds and blue-violet; purple is the appearance of combined colors from nitrogen ions and helium; neon produces the very rare orange. The ionosphere is home to most aurorae borealis, with 100-300 km being typical (this is where green is usually seen, with red at the top); however, some particularly energetic particles penetrate much deeper into the atmosphere, down to perhaps 80 km or lower (purple often comes from here).

Viewed from space, when the northern lights are intense they appear as a ring (an oval actually), the auroral zone, with the north magnetic pole near the center.

The University of Alaska Fairbanks' Geophysical Institute has a good FAQ on the aurora borealis.

Magnetic fields plus solar wind … so you'd expect aurorae on Jupiter and Saturn, right? And auroral displays around the magnetic poles of these planets are now well documented. Aurorae have also been imaged on Venus, Mars, Uranus, Neptune, and even Io.

Some Universe Today stories on aurorae – borealis, australis, … and extra-terrestrial: What are the Northern Lights?, Aurora Reports from Around the World, Behind the Power and Beauty of the Northern Lights, Northern & Southern Aurorae Are Siblings, But Not Twins, Two Rockets Fly Through Auroral Arc, Chandra Looks at the Earth's Aurora, First Aurora Seen on Mars, and Saturn's "Dualing" Aurorae.

Filed under: Astronomy | Comments Off

The splendid aurora borealis. Image Credit: APOD

If you've ever seen the northern lights in person, you'll likely agree that they are one of the most fascinating things about looking up at the night sky. The northern lights are actually caused by the "weather" outside of the Earth's atmosphere, and are a visual reminder of our link to the Sun. The aurora borealis and aurora australis, or what's more commonly called the "northern lights" and "southern lights" respectively, are a fascinating phenomenon here on Earth that is caused by an interaction of the Earth's magnetic field with particles streaming out from the Sun.

The aurorae actually start at the Sun; that is, charged gas particles – plasma – from the Sun are ejected, and makes their way towards the Earth. The plasma takes between 2-3 days from when it leaves the Sun to its arrival at the Earth. This stream of particles is almost constantly being produced by the Sun, and when you hear astronomers talk about the "solar wind" this is what they mean. During the peak periods of the Sun's activity, there is an increase in the occurence of aurorae.

An artist's rendering of the interaction of the Sun and our magnetosphere. Image Credi: NASA

Once the plasma arrives at the Earth, it interacts with our  magnetosphere, causing the charged particles to flow down the magnetic field lines towards the poles, where the magnetic field is weakest. Once the particles enter the atmosphere, they interact with the gases present there. The different colors of the aurorae are produced by interaction with different gases. The most common color, a yellowish-green is produced by the interaction with oxygen miles between 60-150 miles above the Earth's surface. Nitrogen produces blue or purplish-red aurorae below 60 miles, and rare all-red aurorae are produced by high-altitude oxygen about 200 miles up.

Where can you seen the northern lights? They are normally seen near the poles, but they are visible during times of increased solar wind as close to the equator as Mexico. In places like Alaska, Norway and Siberia, the northern lights are often seen every night of the week in the winter (they occur all the time, but are only visible when it's rather dark). The southern lights are not often seen, as the area where they occur most often lies in a sparsely inhabited ring around Antarctica and the southern Indian Ocean.

If you want to go out and see the aurorae, there is a website maintained by the Geophysical Institute of Alaska that actually forecasts whether or not they will be visible in your region. To learn a lot more about the space weather that causes the northern lights, you can visit the THEMIS website, a NASA mission that is currently studying space weather in great detail. The 42nd episode of Astronomy Cast also discusses Earth's magnetosphere and the northern lights.

Filed under: Astronomy | Comments Off

For his next big plan for the private space industry, Richard Branson is thinking up new ways to excite affluent space tourists: flying them into the biggest lightshow on Earth, the Aurora Borealis. Although the New Mexico Virgin Galactic Spaceport isn't scheduled for completion until 2010, the British entrepreneur is already planning his next project intended for cruises into the spectacular space phenomenon from an Arctic launchpad.
Read more…

Filed under: Space Tourism | 15 Comments »