Archives of Ask A Scientist!

About "Ask A Scientist!"

On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 10 March, 2005 Next Week's Question
Collison of particles, gases causes aurora borealis
Question
What is the aurora borealis and why does it occur?

Question
This is a great question. Aurora are beautiful shimmering curtains of colored light seen in the night sky close to the Earth's magnetic poles. The Earth has two magnetic poles hence the two names aurora borealis, commonly known as the "Northern lights" and aurora australis commonly known as the "Southern lights".

Aurora are caused by particles from our Sun colliding with gases in our atmosphere. The sun has many storms on its surface. During these storms clouds of solar particles are thrown out into space. The particles travel at very high speeds, up-to 1000 kilometers per second (compared to a jet that flies at a mere 900 kilometers per hour or one quarter of a kilometer per second!). But the sun is 150 million kilometers away from the Earth and even at these speeds it still takes the particles nearly two days to reach us. When the particles arrive at the Earth they are captured by the Earth's magnetic field and guided down towards the two magnetic poles. The particles collide with gases high up in the Earth's atmosphere at a height of around 100 kilometers above the ground i.e you'd need a sky-scraper with 33,000 floors to reach it. Some of the energy from the collision is converted into light. For you to see an aurora it takes around 100 million collisions! A red aurora is the result of collisions between solar particles and nitrogen gas and a green color is caused by collisions with oxygen gas.

Any planet or moon that has both an atmosphere and magnetic poles will have auroras. Auroras have been seen on Saturn, Jupiter, Uranus and Neptune. On Jupiter's moon Io there can be aurora due to collisions between particles and gas emitted by active volcanoes on the moon's surface!

For more details about aurora visit the exploratorium.

To see many beautiful pictures of aurora both on Earth and in space go to the NASA astronomy picture of the day web site.

Related Questions