Dangerous Space
This is the text version of the interactive 3D documentary. 한국어
Danger ranking › Extreme objects
WR 104
Extreme objects #1 · A gamma-ray burst candidate — the question is whether its jet points at Earth
View in 3D- Name
- WR 104
- Type
- Wolf–Rayet binary
- Size
- Two heavy stars orbiting each other about every 8 months
- Distance
- about 8,000 light-years from Earth · light takes 8,000 years (The estimate varies a lot)
The story in 2 scenes
A cosmic pinwheel
This pair of stars lies about 8,000 light-years away in the direction of Sagittarius. In 1999, the Keck telescope photographed dust from the two stars curling around like a pinwheel. Because the spiral looked almost face-on, some scientists concluded that the pair’s spin axis points toward Earth.
Why?Stars like these may end their lives with a gamma-ray burst. A gamma-ray burst sends its energy out in a narrow jet along the spin axis — so the direction of that axis is the danger direction.
What nextA direct hit from a jet within a few thousand light-years could strip away a lot of the ozone layer. That is why WR 104 became known as “the star aimed at Earth.”
See this scene in 3D →It may miss us
Observations published in 2018 found that the pair’s orbit is tilted about 30–40 degrees from our line of sight. That means the jet probably does not point straight at Earth.
Why?A gamma-ray burst jet is only a few degrees wide. If the axis is tilted even a little, Earth ends up outside it.
What nextIt is not certain when this star will explode, or whether it will make a gamma-ray burst at all. Astronomers are still watching it.
See this scene in 3D →Sources
Impact-threat rankings and probabilities follow NASA/JPL’s Sentry risk table (as of 2026-11-04). The other categories are editorial rankings using the published criteria. Distances to stars can carry large uncertainties.