Northern lights may be visible again in parts of southern Canada, U.S. this week

The Northern Lights are seen in Fredericton on May. 11, 2024. (Hina Alam /The Canadian Press via AP)

Stargazers may have another chance to see the northern lights over the next few days in Canada and parts of the United States.

The spectacular light show, known as the northern lights, aurora or aurora borealis, could be visible across most of Canada, many northern U.S. states, and some lower Midwest states to Oregon starting Monday night, according to a U.S. National Oceanic and Atmospheric Administration (NOAA) geomagnetic storm advisory and maps.

The likelihood of seeing the northern lights is expected to be lower for areas along or near the U.S.-Canada border heading into Tuesday, the forecast shows.

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What causes the northern lights?

The NOAA issued a G3 geomagnetic storm watch, the third highest level, for Monday to Wednesday.

Geomagnetic storms have five ratings based on the severity of their impact, from G1 (minor) to G5 (extreme). The sun's energy and electrically charged particles cause the northern lights, which usually present as a milky greenish colour.

Eruptions of solar material, called coronal mass ejections (CMEs), occurred during the weekend. CMEs can result in a geomagnetic storm that presents as the northern lights when they arrive to Earth.

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The CMEs are expected to arrive as early as Monday. Minor or G1 storm levels may happen Monday, but more CMEs are expected Tuesday, which could lead to G2 or G3 storm levels, resulting in a higher chance of seeing the northern lights.

The light spectacle may still be visible later this week as elevated solar activity could continue past Wednesday.

CTV News science and technology specialist Dan Riskin has said previously that the best place to view the northern lights is away from bright city lights.

Auroras are typically seen after sunset or just before sunrise.