New Look at the Infant Universe
From ESA’s HubbleCast. In early 2009, a team of astronauts visited Hubble to repair the wear and tear of twenty years of operating in a hostile environment — and to install two new instruments, the Cosmic Origins Spectrograph, and Wide Field Camera 3 — better known as WFC3.
Hubble has become famous for its striking visible-light pictures of huge clouds of interstellar dust and gas. But sometimes scientists want to know what’s happening behind, or inside, the cloud of dust. Making infrared observations pulls away the veil and reveals the hidden stars.
Until now, infrared imaging was challenging with Hubble. The Near Infrared Camera and Multi-object Spectrometer, or NICMOS, did allow astronomers to study objects in infrared light in ways not possible from the ground, but it forced them to make a difficult choice. Because its images were small — only about 65 000 pixels in total, similar to a mobile phone screen — NICMOS could produce the sharpest images only if it concentrated on a very narrow field of view. Taking in a wider view came at the cost of losing much of the detail.
These improvements mean Hubble is now far better at observing large areas of sky as well as very faint and very distant objects. These are key for the science of cosmology, the study of the origins and development of the Universe.
Because the Universe is expanding, light waves coming from distant objects are stretched as they travel through space, and the waves become longer. The further an object is away, the more its light is stretched on its journey to us, and the redder the light appears. Hence the effect is known as redshift.
For really distant objects, the ultraviolet and visible light is redshifted so much it goes infrared — literally, “below red” — and that is the reason that infrared imaging is so important for spotting these very distant galaxies.
This is the Hubble Ultra Deep Field, a visible light image taken in 2003 and 4 with Hubble’s Advanced Camera for Surveys.