The acronym IRAS stands for Infrared Astronomical Satellite, which was launched by NASA in 1983 to conduct an infrared survey of the entire sky. Synonyms for IRAS include 'space telescope' and 'infrared observatory'. However, there are also other observatories that use infrared detectors and produce infrared images, such as the Spitzer Space Telescope and the Herschel Space Observatory. These could also be referred to as alternatives or rival infrared telescopes, but are not direct synonyms for IRAS as they have different capabilities and missions. Nonetheless, IRAS remains an important tool for astronomers to study the infrared radiation emitted by celestial objects and advance our understanding of the universe.