Editor’s notice: An extra clarification has been edited in from the creator in response to a follow-up query post-publication.
How removed from Earth would a telescope should be to seize a direct view of the black hole on the middle of the Milky Way, unimpeded by dust clouds?
Dan Nicolaescu
Clifton Park, New York
On the middle of our galaxy sits a supermassive black hole often called Sagittarius A*, or Sgr A* for brief. This black hole was first found in 1974 as a pointlike radio supply. Sgr A* can’t be seen with an optical telescope as a result of, as you level out, interstellar dust and fuel clouds within the aircraft of the Milky Way obscure any radiation coming from the middle of the galaxy.
This dense ring of molecular fuel orbits with 10 to twenty light-years of Sgr A*. So, if one was inside this distance to the black hole, Sgr A* needs to be observable.
Alternatively, the orientation of the ring is roughly alongside the aircraft of the galaxy. Subsequently, if Sgr A* is noticed at an angle away from the disk of the galaxy, somebody ought to have the ability to see the middle of the galaxy in seen gentle.
However there’s presently no reasonable manner for us to get an optical telescope shut sufficient to Sgr A* that the dust and fuel wouldn’t be an issue. Keep in mind, the farthest human-made objects are the Voyager spacecrafts, which launched in 1977 — neither of which have definitively handed exterior the solar system on the time of writing.
If we had been involved with a complicated alien civilization close to the middle of the galaxy, theoretically they might ship us a picture. However, within the meantime, researchers have provide you with an excellent higher answer: the Occasion Horizon Telescope (EHT). You’ve most likely already seen the information by now: The EHT revealed the primary picture of Sgr A* earlier this 12 months, on Could 12. This was simply the second time the world has ever seen a black hole — the primary was M87*, three years prior.
The EHT is a world array of 11 telescopes. As an alternative of optical gentle, these telescopes can see in radio wavelengths, that means they will peer previous the dust and fuel and see the black hole. Or, extra precisely, they will see the very shiny materials swirling into the black hole, often called the accretion disk. The shadow of the black hole’s event horizon — the purpose of no return, the place not even gentle can escape the item’s gravity — seems silhouetted in opposition to the accretion disk.
Due to its proximity and mass (roughly 4 million instances that of the Solar), Sgr A* presents an unparalleled alternative to check how physics behaves underneath such excessive gravity. It additionally gives a improbable alternative to check how materials is captured, accreted, and ejected by a black hole.
Farhad Yusef-Zadeh
Professor, Division of Physics and Astronomy, Northwestern College, Evanston, Illinois
