A dark figure spreading its wings against a starry backdrop: the “Cosmic Bat” nebula has been captured in beautiful detail by the European Southern Observatory (ESO).
The Cosmic Bat, formally known as NGC 1788, is two thousand light-years away in a dark corner of the Orion constellation. The nebula does not give off any light of its own, as it is what is called a “reflection nebula” meaning it is a cloud of dust and gas that it illuminated only by the light of nearby stars. In the case of the Bat, the illumination comes from a cluster of young stars at its core.
In order to capture this dim nebula, a powerful telescope was required. The ESO used its Very Large Telescope (VLT), part of the Paranal Observatory in the Atacama Desert of Chile, which sits at a high altitude — 2,635 m (8,645 ft) above sea level. The site has very low levels of light pollution as the nearest community to the observatory is the tiny hamlet of Paposo, population 259, which is located 38 kilometers (24 miles) away.
This means the VLT is able to capture very dim or very distant phenomena using its 8.2m diameter mirrors, with minimal blurring caused by Earth’s atmosphere.
This particular image of the Cosmic Bat is the most detailed image of the nebula ever taken since it was first catalogued by astronomer William Herschel in 1888. It was selected as a target for imaging in celebration of the twentieth anniversary of one of ESO’s instruments, the FOcal Reducer and low dispersion Spectrograph 2 (FORS2).
The FORS2 instrument, mounted on one of the VLT’s telescopes, is a versatile tool which can take spectra of one of more objects simultaneously. As a spectrograph it can disperse light into a rainbow of different wavelengths to allow astronomers to study the chemical composition of distant objects. And it can also image large areas of the sky with high sensitivity, creating beautiful images like this one of the Cosmic Bat.
