Small Magellanic Cloud
What is Small Magellanic Cloud?
Galaxies· Distance ~200,000 ly. The Large Cloud's smaller partner, a naked-eye smudge in southern skies. In 1912 Henrietta Leavitt compared its variable stars and discovered the Cepheid period–luminosity relation — the yardstick that lets us measure the universe.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Small Magellanic Cloud is in your sky right now: https://nowsky.org/solar/sky?sel=small magellanic cloud — location and time set automatically, no login.
Its place in the sky
A galaxy, in the direction of Hydrus, spanning about 320 arcminutes of sky — 10 times the width of the full Moon.
Distance and scale
| Distance | ~200,000 ly |
|---|---|
| Diameter | ~7,000 ly |
| Stars | a few hundred million |
| Where | southern skies, in Tucana |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Discovery and name
Here Henrietta Leavitt found the Cepheid period-luminosity law in 1912 — the key to cosmic distances.
Frequently asked
- How far is Small Magellanic Cloud from Earth?
- ~200,000 ly.
- How big is Small Magellanic Cloud?
- ~7,000 ly.
- Where in the sky is Small Magellanic Cloud?
- In the direction of Hydrus.
- Where is Small Magellanic Cloud in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
A galaxy split front and back
The Small Magellanic Cloud looks like a single cloud in the sky, but measuring its stars' distances reveals two bodies overlapping along the line of sight. The near and far parts are separated by thousands of light-years, and the distance distributions of Cepheids and red giants show the two peaks. The Large Cloud's tides are thought to have stretched the small galaxy out, and the gas and stars of the "Magellanic Bridge" joining the two were torn loose in the process.
The stretching continues. The Small Cloud is predicted to be absorbed by the Large Cloud, or both to merge with the Milky Way, within billions of years. This was the galaxy Leavitt assumed to lie "at one distance" when she found the Cepheid relation; it is now clear that the assumption held only to within thousands of light-years — and yet her conclusion stood, because the galaxy is so far away that the error was too small to change the result.
The galaxy in depth
The Small Magellanic Cloud is a dwarf irregular galaxy about 200,000 light-years away, appearing as a faint cloud a few moon-widths wide in Tucana. Some 7,000 light-years across with a few hundred million stars, it is far smaller than its Large companion. It was probably once a barred spiral, distorted by the tides of the Milky Way and the LMC, and a bridge of hydrogen still links it to the larger Cloud.
This little galaxy is one of the starting points of modern cosmology. Henrietta Leavitt at Harvard identified thousands of Cepheid variables in it on photographic plates and, since all lay at the same distance, showed in 1912 that longer periods mean brighter stars. Hubble used that relation to measure the distance to Andromeda and prove that galaxies lie beyond our own. Next to the SMC shines 47 Tucanae, the sky's second-brightest globular cluster, though it belongs to the Milky Way and is a much closer foreground object.
It cannot be seen from mid-northern latitudes. Set the Sky view's location to a southern city and the SMC appears between Achernar and the south celestial pole, west of the Large Cloud. On a moonless night it is plain to the naked eye, like a fragment torn from the Milky Way.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.