Wayward Asteroid Photobombs Hubble Snapshot of Galaxy UGC 12158

This Hubble Space Telescope image of the barred spiral galaxy UGC 12158 looks like someone took a white marking pen to it. In reality it is a combination of time exposures of a foreground asteroid moving through Hubble's field-of-view, photobombing the observation of the galaxy. Several exposures of the galaxy were taken, what is evidence in the dashed pattern.

The asteroid appears as a curved trail due to parallax: because Hubble is not stationary, but orbiting Earth, and this gives the illusion that the faint asteroid is swimming along a curved trajectory. The uncharted asteroid is in inside the asteroid belt in our solar system, and hence is 10 trillion times closer to Hubble than the background galaxy.

Rather than a nuisance, this type of data are useful to astronomers for doing a census of the asteroid population in our solar system.

About the colours

These images are a composite of separate exposures acquired by the ACS instrument on the Hubble Space Telescope. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Blue: F475W, Green: F606W, Red: F814W.

About the data

The HST observations include those from program 10182 (A. Filippenko). Image Processing: Joseph DePasquale (STScI)