FAQ
What causes the aurora?
The aurora originates from solar activity. Storms on the surface of the sun release charged particles. Some of these charged particles are captured by the Earth's magnetic field, where they accelerate along the Earth's magnetic field lines towards the north and south poles. When these charged particles collide with the oxygen and nitrogen in Earth's atmosphere, the collisions release energy in the form of light, and this is the visual display we call the aurora.
Why are all of these images black and white? I thought the aurora was green.
These images are 'white light' auroral images that capture the intensity and the shape of the aurora, but not the color. The colors of observed aurora are a consequence of the specific particles interacting in the upper atmosphere; the green commonly observed indicates the presence of oxygen.
What is the THEMIS mission?
THEMIS is an acronym for Time History of Events and Macroscale Interactions During Substorms. The THEMIS mission consists of five spacecraft that collect solar wind data as they orbit Earth, along with an array of ground-based all-sky imagers. The image data we are using here is produced by these ground-based all-sky imagers. You can read more about THEMIS at the THEMIS mission website.
Why do we care about the shape of the aurora?
The phenomena that lead to the aurora are well-understood in a general sense, but the causes of the smaller-scale shapes captured in these images and their relationship to the underlying magnetospheric processes are not understood. Classifying auroral images by shape is a first step in investigating these relationships.
How do I classify an image that could fit into multiple different categories at the same time (an image containing both an arc aurora and a cloud, for example)?
Many images in the dataset fall into multiple categories simultaneously, making the 'correct' classification ambiguous. In these situations, select any and all categories that apply.