← Back to dex
Rare black hole 48 EP

M33 X-7

RA 23.3922° · Dec 30.5358° · blackhole

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 4 badges
48 pts · Rare
Rare 50 pts → Epic
  • Black hole +26
  • X-ray binary: stripping a living star +10
  • Outside our galaxy entirely +6
  • Stellar-mass black hole +6
Total score 48

2 more points to reach Epic.

Badges

  • Black hole · +26
  • Outside our galaxy entirely · +6
  • Stellar-mass black hole · +6
  • X-ray binary: stripping a living star · +10

Trivia

What makes it special

  • It is feeding. Gas spiralling in is squeezed and heated to millions of degrees before it falls, so the disc around it blazes brighter than anything else in the neighbourhood.

Handle with care

  • Spaghettification. Its gravity pulls your feet so much harder than your head that you would be stretched into a thread roughly 914 km out — long before you ever reached the horizon.
  • No way back. Cross the event horizon and every path you could possibly take leads inwards. It is not that you cannot go fast enough — it is that 'out' has stopped being a direction.

What it actually is

  • Where it lives. It sits at the very heart of Triangulum Galaxy (M33).
  • What it is. A stellar-mass black hole: what is left behind when a star far heavier than the Sun exhausts its fuel and its core collapses in less than a second.
  • It is eating a star. It is stripping a living star: gas peels off its companion and spirals in, heated so fiercely on the way down that the disc glows in X-rays.

Sense of scale

  • In perspective. Further than Andromeda, the most distant thing the unaided human eye can see.
  • Its event horizon. The point of no return sits 46.2 km out, making the horizon about 92.5 km across.

Properties

accreting
yes
bh class
stellar
constellation
Tri
dist ly
2730000
first imaged
no
gw detection
no
host galaxy
Triangulum Galaxy (M33)
is sgr a
no
mass solar
15.65
name
M33 X-7
named
no
schwarzschild km
46.23
spin
0.84
xray binary
yes

About M33 X-7

M33 X-7 is a rare black hole. It lies about 2,730,000 light-years from Earth and sits in the constellation Tri.

Gas spiralling in is squeezed and heated to millions of degrees before it falls, so the disc around it blazes brighter than anything else in the neighbourhood.

How to see it

Look for M33 X-7 in the constellation Tri.

Like any astronomical target, M33 X-7 is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why M33 X-7 is a rare black hole

M33 X-7 scores 48 points on Spacedle's rarity scale, which places it in the rare tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Black hole, Outside our galaxy entirely, Stellar-mass black hole and X-ray binary: stripping a living star — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.