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The star Betelgeuse is doing something. Something important. No one is sure what it means, but it has our attention and we want to keep our telescopes focused on it. Except that this Summer, we can’t.

What’s next for Betelgeuse? [NOTE: Image distorted by minor camera movement.]

Whatever is happening with the soon-to-be supernova Betelgeuse currently, it is critical astronomers and astrophysicists maintain close observation of the progenitor star. It may be decades, centuries, or millennia before it collapses and explodes into a spectacular show for our planet nestled some 640 lightyears away, and yet, at this moment, it is displaying behavior that may give us the first opportunity to learn what a supernova does before it does its supernova thing.

Betelgeuse and its parent constellation, Orion, are victims of the Earth’s orbit around the Sun. For two months in the Summer (approximately Cinco De Mayo to Independence Day in the U.S.) the constellation is on the opposite side of the Sun from Earth. Astronomers will not be able to see the star at a time that may be crucial to understanding pre-supernova behavior.

Betelgeuse is a variable star that is undergoing a historic expansion, cooling, and dimming (fainting) phase. That process is likely near the end. Next up should be a contraction, warming, and brightening phase. That process will take months…right into Summer. When the curtain drops on Betelgeuse in May, Earth-bound astronomers and astrophysicists will be an audience without a show to watch.

Graphic 1.0 – Betelgeuse variable star cycle (hypothetical 2020 brightening cycle in blue.)

There are multiple possibilities for what might happen. Betelgeuse might increase in brightness over several weeks or months as it has in the past, then resume a normal cycle. It might brighten, but not to the magnitude it has in past cycles. The star might keep brightening to a greater magnitude than it has in the past. Betelgeuse might also brighten suddenly and begin its short-lived supernova phase. No one knows.

What is known is that astronomers will be observing Betelgeuse as long as possible. We will know if something major happens this Summer through other electromagnetic observations and non-Earth bound observation sources, but for amateur astronomers, we will have to wait and not see.