U.S. astronaut Scott Kelly has been tweeting amazing images of the Northern Lights under #YearInSpace. The Twitter postings were made from the International Space Stations (ISS). Colors shown included purple, orange, green, and red.

The light display occurred on Wednesday over the skies of Canada and the northern United States. Residents in North Dakota, Minnesota, Michigan, and upper Maine were able to see the aurora. Besides sharing photos, Kelly tweeted a video as well.

Scott Kelly has been in space since March 27, and will be returning to Earth one year later. He is currently joined by Russian cosmonaut Mikhail Kornienko for the year-long mission, which is twice as long as the average U.S. mission.

What Are Auroras (Northern Lights)

Commonly known as auroras on earth, the dancing lights can be seen at both the Arctic and Antarctic regions. Depending on the viewer's location, the auroras can either be called Northern or Southern Lights. Auroras are also known by their official name, aurora borealis.

According to scientists, the lights are the result of electromagnetic fields generated by solar flares striking the Earth's atmosphere.

What makes Scott's vantage point so special is that he sees lights brighter than those appearing on Earth. Based on height, gas particles react differently. At lower attitudes, oxygen creates yellow or green light. Higher up, the light is red.

Scott tweeted that this was his first time seeing a red aurora, and wrote down the word "spectacular". Red lights are rarely seen by people on Earth.

What is Scott Kelly Doing in Space

The 51-year-old Nasa veteran is part of a landmark study that investigates the long-term effects of zero-gravity on the human body.

Meanwhile, Kelly's identical twin brother Mark is staying on earth as the control subject. The two men share the same DNA, which will help researchers gain more accurate information after Scott returns. Twins are sometimes used in medical research in order to reduce variables in experimentation.

Researchers plan to use data obtained from the Kelly twins in future endeavors, such as the first manned mission to Mars.

Like Scott, Mark is also a member of the NASA fraternity. Both brothers had piloted the U.S. space shuttles before their retirement. Scott continues to be an astronaut, while Mark has left the space program.

Prior to being selected for NASA missions, the twins had been serving in the U.S. Navy as aviators. Scott has logged more than 8,000 flight hours in more than 40 different aircraft. At this time, both brothers are retired from the U.S. navy.