NGC 300

NGC 300, also known as Caldwell 70 or the Sculptor Pinwheel Galaxy, is a spiral galaxy located in the constellation Sculptor. It was discovered on August 5, 1826, by Scottish astronomer James Dunlop. This galaxy is one of the closest to our own galaxy group, the Local Group, and is thought to lie between this group and the Sculptor Group.

NGC 300 is the brightest of the five main spiral galaxies in the direction of the Sculptor Group. When viewed from Earth, it is tilted at an angle of 42 degrees and shares many features with the Triangulum Galaxy. It is about 94,000 light-years wide, which makes it somewhat smaller than our own Milky Way. Estimates suggest that NGC 300 has a mass of roughly (2.9 ± 0.2) × 10¹⁰ M_☉, showing it is a large and important object for astronomers studying galaxies.

Nearby galaxies and group information

NGC 300 and the barred spiral galaxy NGC 55 have often been considered part of the Sculptor Group, a nearby group of galaxies. But newer measurements show that these two galaxies are actually closer to us and likely form a pair that moves together.

The small galaxy called Sculptor C is about 6.65 million light-years from the Sun and is probably a smaller galaxy that orbits NGC 300.

Distance estimates

Astronomers have tried to figure out how far away the galaxy NGC 300 is from us. In 1986, they thought it was about 5.41 million light-years away. By 1992, they updated this to about 6.9 million light-years. Later measurements in 2006 suggested it might be around 7 million light-years away. Different methods, like studying bright stars and variable stars, helped scientists get more accurate estimates. Today, the best guess is that NGC 300 is about 6.07 million light-years from us.

Transient Events

Astronomers have observed several bright explosions, called transients, in the galaxy NGC 300. These explosions appear suddenly and change over time. One notable event, called SN 2010da, was discovered in 2010 and faded quickly. Another event, SN 2020acli, was found in 2020.

In 2008, an amateur astronomer discovered a bright explosion named NGC 300-OT. This event stood out because it was not as bright as a typical supernova but was brighter than a usual nova. Its brightness changed slowly over several months. Scientists believe this explosion might have come from a low-mass star merging with another star. More recently, in 2025, this event was classified as an Intermediate-Luminosity Red Transient.

Astronomical objects

An x-ray source in NGC 300, called NGC 300 X-1, might be a special pair of stars orbiting each other. One is a very heavy star, and the other could be a black hole. They circle each other every 32.8 hours.

There is also a rare type of very hot star, called STWR 13, in one of the bright areas of NGC 300 where new stars are born.