What would happen if a black hole jet hit the sun or Earth?
Herman D鈥橦ondt
Sydney, Australia
Advertisement
As in real estate, it is all about location, location, location. The effects of a jet produced by an active black hole depend very much on how close we are to the black hole and its size. The larger the black hole, the larger the jet. Are we talking about a stellar black hole or a supermassive one? In all cases, if it is far enough away, we need telescopes to notice it. Close enough, and the entire solar system could be fried to a crisp.
Consider a somewhat less extreme example: rotating neutron stars, otherwise known as pulsars. These stars contain the mass of several suns in an object the size of a city. Most of them rotate several times per second or faster. Like black holes, they can emit beams of radiation as well as jets of particles from their poles. Those particles travel at around half the speed of light.
Some of those jets are aimed at Earth. That is how pulsars were discovered, when in 1967 Jocelyn Bell noticed extremely regular radio pulses coming from a point in space. After eliminating the idea that the pulses were an alien signal (jokingly dubbed LGM-1, for 鈥渓ittle green men鈥�), it was found that they happened when the beam of a pulsar sweeps over Earth.
Apart from radiation, these stars can also emit jets of nuclear particles, and even anti-particles. Unlike radiation, particle beams are affected by the magnetic fields in interstellar space. This means they defocus more rapidly than beams of radio waves. We have detected such a beam from at least one pulsar, but its beam isn鈥檛 aimed at us, and it is much too far away to affect us.
Because we are here, we can confidently state that Earth has never been close enough to a pulsar to be harmed by its jets 鈥� or by the supernova explosion that created the star 鈥� so it is unlikely to happen in the foreseeable future.
The chances of our world being in the beam path of a nearby supermassive black hole are far smaller still, as there are no galaxies with active black holes nearby.
To answer this question 鈥� or ask a new one 鈥� email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.