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I wouldn’t try to measure much in Earth diameters besides other planets. An AU is much more efficient for measuring things the size of a star system, like black holes. (And solar masses is helpful for star sizes of course.) 1 AU = 11,740.7 Earth diameters, so that black hole is like 9 million Earth diameters, if my quick math is correct (not my strong suit lol).

Did I misunderstand your question?

> How big is the supermassive black hole S50014+81 compared to Earth?

To answer that, we divide the black hole's "size" by Earth's "size." And by "size," I think you mean something like diameter. So, the formula is H ÷ E.

This is a really simple formula, but we have to make sure we're using the same units for it to work.

• The diameter of Earth is 12,756.3 km.

• The black hole's diameter is 1,582 AU, which is a unit of length (like meters), but is still a different unit than kilometers.

So, we either have to convert Earth's size from km to AU, or convert the black hole's size from AU to km. (Let's do the latter.)

1 AU = 149,597,870.7 km

So, the size of the black hole is 1,582 × 149,597,870.7 = 236,663,831,447.4 km.

Now that both are in the same units, we can go back to the original formula and plug in our numbers:

H ÷ E becomes 236,663,831,447.4 km ÷ 12,756.3 km = 18,552,701.9 km.

Thus, the black hole is about 18.5 million times as big as Earth.

Thank you for giving a full explanation! And yes you were right I did mean diameter but couldn't think of the word haha. Thank you, I appreciate it!

No no you didn't misunderstand, I just thought that AU's were used for measuring space objects wayy bigger than Earth. Thank you for answering though!

Yep! Or maybe even measure this as 0.01265 light-years to appreciate the size, because 800 AU is massive. Pluto’s semimajor axis is less than 40 AU.

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AU is NOT used to measure size. It is used to measure distance. 1 AU = the distance of the Earth from the sun (93 million miles). This is not size. It is a distance. It's the same concept why we use different measuring standards. If measuring the length of you table, you use inches. If measuring how far you throw a football, you use yards. If measuring how far you drive, you use miles. AU is just a measurement standard. It makes taking about large distances easier without the numbers being too large to be hard to use and conceptualize. If I drove from one city to another, which is 320 miles away, what if I gave you that distance in inches? It's a huge number and difficult to deal with. After AU, the standard we use is light years.

Size and distance are just the same thing. Stop being overcorrect.

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Hello u/VesperalRhino, your submission "Supermassive Black hole S50014+81" has been removed from r/space because:

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