3I/ATLAS (annotated)

This image of interstellar comet 3I/ATLAS was captured by the Hubble Space Telescope’s Wide Field Camera on 21 July 2025.

The scale bar is labeled in arcseconds, which is a measure of angular distance on the sky. One arcsecond is equal to an angular measurement of 1/3600 of one degree. There are 60 arcminutes in a degree and 60 arcseconds in an arcminute (the full Moon has an angular diameter of about 30 arcminutes). The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope.

The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above).

This image shows visible wavelengths of light.