Triangulum (M33) is the third large galaxy of the Local Group, a loose, gas-rich spiral seen nearly face-on and one of the most distant things visible to the eye.
At a glance
| type | galaxy |
|---|---|
| distance from the Sun | 2.74 million light-years (840 kpc) |
| its light left it | 2.74 million years ago |
| size in the piece | about 59,000 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About Triangulum (M33)
Triangulum is a spiral galaxy smaller than both the Milky Way and Andromeda, with only a modest central bulge and patchy, loosely wound arms. It is seen fairly close to face-on, so its whole disc is spread out to view. Under exceptionally dark skies, sharp-eyed observers can glimpse it without optical aid, though its light is spread so thinly that it is easily lost.
It is rich in gas and still forming stars actively. Its arms are dotted with bright HII regions, clouds of hydrogen lit by young massive stars, and one of them is among the largest star-forming regions known in the Local Group. Because the galaxy is close, nearly face-on and relatively free of dust, it is a favourite target for studying how star formation is spread across a disc.
What you see in the piece
It fades in on the pull-back near Andromeda, a bluish disc scattered with pink knots of ionised gas, tilted at its measured angle.
Measured or modelled
Whether Triangulum is a bound satellite of Andromeda, and whether the two have interacted in the past, is debated. The extent drawn here is modelled.
Questions
How far away is the Triangulum Galaxy?
Triangulum is about 2.74 million light-years (840 kpc) from the Sun.
Can you see the Triangulum Galaxy with the naked eye?
Only under exceptionally dark skies, and only just. It is large on the sky but very faint per patch, so binoculars from a dark site show it far more easily.