The image is natively 10750x7167px but is shown here at 60% of its size as a PNG.

IC 1805, also known as the Heart Nebula, is an emission nebula, an HII region, and an open cluster located approximately 6,500 light-years from Earth in the constellation Cassiopeia, within the Perseus Arm of the Milky Way.

It spans a field of about 60 arcminutes, or roughly 200 light-years in diameter.

This nebula is associated with the open cluster Melotte 15, which lies at the heart of the structure and is responsible for ionizing the surrounding gas with its ultraviolet radiation.

It is part of a larger complex with the Soul Nebula (IC 1848), forming the Heart and Soul Nebula pair.

The Heart Nebula is characterized by ionized hydrogen gas, as well as oxygen and sulfur components, which produce red, blue, and orange hues in narrowband images.

It is also associated with the larger W3/W4/W5 complex, where it forms the brightest part of a stellar superbubble known as the W4 Superbubble.

The nebula spans an apparent size of about 1° to 2° in the sky, or two to four times the diameter of the full Moon.

It was discovered in 1787 by astronomer William Herschel, who identified its brightest part as NGC 896.

It is also known as Sh2-190, W4, or IC 1805.

Although the open cluster IC 1805 has a magnitude of 6.5, the nebula itself is much fainter, with an apparent magnitude of about 18.3, making it very difficult to observe with the naked eye or even through a telescope, even a large one. To photograph it effectively, a long exposure, often in H-alpha, is necessary, particularly to reveal the details of the ionized gases.