The answer is not simple and depends on the distance between the exploding star and our planet.
The phenomenon of exploding stars, also known as supernovae, has always intrigued us with their powerful explosions and brilliant light that can illuminate an entire corner of the universe. But are these massive explosions really a threat to Earth? The answer is not straightforward and depends on the distance between the exploding star and our planet.
Do Stars Really “Explode”?
If we consider it broadly, our Sun also “explodes” regularly, especially during periods of heightened activity. Events such as solar storms or coronal mass ejections are smaller explosions that release a large amount of charged particles and radiation. These events typically only cause disruptions in radio waves, displace satellites from their orbits, or create stunning auroras. However, if a massive solar storm directly impacts Earth, it could severely damage electrical systems and telecommunications technology. This is why scientists continuously monitor the Sun’s activity.
The Eta Carinae Nebula surrounds one of the largest stars in our Milky Way after an explosion in the 19th century.
However, these types of “explosions” are minor. Some stars that are much larger than the Sun can undergo supernova explosions – events that mark the end of a massive star’s life. This is an extremely violent astronomical phenomenon, where a star shines brighter than the entire galaxy for a brief period, simultaneously releasing vast amounts of energy and radiation.
When Does a Supernova Actually Become a Danger?
A supernova is only truly dangerous if it occurs at a close distance to Earth. The “close” distance is typically defined as within about 30-50 light-years. If a star explodes within this range, the intense radiation from the explosion could scorch the atmosphere, destroy the ozone layer, and leave Earth exposed to harmful ultraviolet radiation from the Sun. This effect could last for thousands of years, causing serious consequences for life.
Additionally, high-speed protons and electrons from the explosion would continuously “attack” Earth, increasing the risk of cancer in living organisms and causing unpredictable climate changes. If the explosion is even closer, the extreme heat and light could raise Earth’s temperature as if we had a “second Sun,” leading to the collapse of global ecosystems.
The remnant of the Kepler Supernova, the most recent known supernova in the galaxy. At a distance of 20,000 light-years, there are no negative consequences for us.
What Distance Is Safe?
If a supernova occurs at a distance greater than 200 light-years, its effects on Earth would be minimal, nearly negligible. This is due to the “inverse square law”: the intensity of radiation decreases with the square of the distance. For example, a supernova 200 light-years away would only be as dangerous as 1/40 of an explosion that is 30 light-years away.
Fortunately, the nearest star that could become a supernova in the future is Betelgeuse, which is approximately 530 to 900 light-years away – far enough to pose any serious threat. Nevertheless, it would still be a breathtaking sight, as the light from the explosion could be clearly visible to the naked eye, even during the day.
While typical supernovae at a distant range are not dangerous, there are exceptions. Some types of supernovae emit large amounts of X-rays or gamma rays – types of radiation that can severely damage the ozone layer, much more so than chemicals like CFCs. If Earth were to lie within the “beam” of this radiation, even at hundreds of light-years away, the consequences would still be very concerning.
Additionally, rare explosions such as hypernovae or kilonovae – which are many times more powerful than typical supernovae – could pose threats at even greater distances. However, these phenomena are very rare and usually occur in regions very far from Earth.
