Ancient History Is About to Happen in the Night Sky
By Graham Jones. Published 7-Jun-2024. Changed 22-Aug-2024
3000 years ago, a distant star system exploded. We’ll see it happen in our night sky sometime in the next few months.
UPDATE (Aug 22): When Will T Coronae Borealis Erupt?
Last year Brad Schaefer, an astronomer at Louisiana State University, predicted that T Coronae Borealis would erupt around 2024.4 ± 0.3 years. This meant an eruption was most likely to happen in 2024 between February and the end of August—but could also happen outside this period.
T CrB has not erupted yet, and we are nearing the end of the ‘most likely’ prediction interval. “So far, this is all normal enough,” Dr Schaefer told timeanddate.com on August 21, 2024.
“The remaining probability distribution is a tail extending out a number of months,” he added. “The most likely remaining eruption date is ‘soon’, any night now, within the next month or two. It is likely that T CrB will go up before the end of the year.”
A new star is about to appear in the constellation Corona Borealis.
©timeanddate
T Coronae Borealis, aka the Blaze Star
Find T Coronae Borealis using our Interactive Night Sky Map
Every 80 years or so, a binary star system 3000 light years from Earth undergoes a violent outburst.
T Coronae Borealis—also known as T CrB or the Blaze Star—consists of two stars. It is normally invisible to the naked eye.
However, this star system is a recurrent nova. This means it undergoes repeated outbursts where its brightness increases dramatically.
3000 Light Years from Earth
At some point in the next few months, the Blaze Star is expected to live up to its name and shine as a new star within the northern constellation Corona Borealis.
You’ll have to be quick: it will only be visible to the naked eye for a few days.
Also, spoiler alert: the explosion has already happened—about 3000 years ago.
The roughly 3000-light-year distance between T Coronae Borealis and Earth means the light has taken that long to reach us. A light year is a measure of distance. It is the distance that light travels in a vacuum in exactly 365.25 days.
In effect, therefore, we’ll be watching ancient history: the eruption took place 3000 years ago—around the end of the Bronze Age in human history.
And because it recurs every 80 years or so, T CrB will have undergone about another 40 outbursts in the 30 centuries since then.
An Explosion of Hydrogen
One of the stars that make up T Coronae Borealis is a red giant, which is a cool, large star. The other is a white dwarf, which is hotter and smaller.
The dense white dwarf attracts hydrogen from the red giant. When the build-up of hydrogen reaches a certain level, it ignites—producing a bright flash.
“Pre-eruption Dip”
The last two outbursts of T Coronae Borealis were in 1946 and 1866. Historical records suggest that outbursts were also observed in the years 1787 and 1217.
In 2023, astronomers recorded a “pre-eruption dip” in the star system’s brightness. This indicates an explosion will happen by around September 2024.
Find the Corona Borealis Constellation
Arcturus and Vega are helpful signposts for finding Corona Borealis: they are the 4th and 5th brightest stars in the night sky.
©timeanddate
The crown-shaped constellation Corona Borealis—the word corona means crown, while borealis means northern—can be found between the bright stars Arcturus and Vega.
Find T Coronae Borealis using our Interactive Night Sky Map
In the Northern Hemisphere summer, Corona Borealis is overhead during the night. For sky-watchers in the Southern Hemisphere, the constellation is low down toward the north.
When it erupts, the Blaze Star will be visible with the naked eye—for a few days only—as an additional star next to the crown.