Einstein Probe finds two stars that have spent 40 million years taking turns eating each other The Einstein Probe space telescope has spotted evidence of one star consuming matter from another. The first clue that led to this discovery was an X-ray flash emanating from the Small Magellanic Cloud, around 200,000 light years from Earth. The flash was unexpected so scientists were keen to learn more. The flash was spotted …
The full sky is about 40000 square degrees, or deg² (and, of course, 4π sr). Square degrees, square arcseconds and, more rarely, square arcminutes get frequent use in astronomy.
The solid angle of Wales is dependent on one's location, of course. But if you were at the center of a hollow earth, looking up at Wales from the underside, it would cover about 1.66 square degrees.
Let's just say we need to be at the exact distance where we can see things going klabooie and not be taken out by them.
I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.
Like being in the city of Halifax when a ship carrying 7000 tons of explosives caught fire resulting from a collision and blew up. The city became a center for eye injuries, given the amount of people looking at the ship's immolation behind glass windows when it detonated, and where within range.
https://en.wikipedia.org/wiki/Halifax_Explosion
So yeah, it is a bit comforting not being inside the blast radius of the space wedgie* of the week.
*Star Trek reference.
I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.
That only occurs when a giant star goes supernova via a core implosion, where the core then collapses right the way down to a black hole. You tend to get high-energy particles emitted in a pair of very narrow polar jets. These are suspected to be the source of the long-duration gamma ray bursts that hit earth.
> I heard about some stars that emit a lethal jet of radiation through their poles when they go boom, and these were calculated to be lethal for over 1 million LY in the direction they happen to aim.
You are most likley referring to Gamma-Ray bursts (GRBs), but you are off by a couple orders of magnitude. A GRB would most likely have to be within 10,000 LY to be dangerous to the Earth, which basically limits it to having to be within our own galaxy. But since the the events casing GRBs are quite rare (estimated at between 1 in every 10k years and 1 in every 1million years in a galaxy our size) and the jets are tightly focused, you'd be pretty unlucky for a star within 10k LY to be pointing directly at our Solar system when it does go supernova.Which isn't to say it can't or won't, but it is extremely rare and is believed to have happened at least once in our past (4-5 billion years is a long time, long enough for incredibly rare events to have happened a time or 2 or three).
You are correct for a Type 1b, Type 1c or Type 2 supernova - they are all caused by stellar core implosion and the star needs to be at least 8 solar masses to trigger it. However a Type 1a supernova is caused by the deflagration of a white dwarf; it only needs to be somewhere around the Chandrasekhar limit.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
