General overview of some of the science going on at Yerkes Observatory: November 1998.

Infrared Radiation

Until relatively recently, astronomers have been limited to studying objects that either emitted or reflected visible light. Astronomers today are increasing our knowledge of the Universe by studying forms of radiation invisible to the eye, including gamma rays, X-rays, ultraviolet, infrared, and radio waves. Although dust blocks visible light from objects such as young stars, edge-on galaxies, and the center of our own galaxy, infrared and radio waves penetrate the dust and allow astronomers to study these sources.

Nearly everything in the Universe, from the coldest clouds of interstellar dust to the jets from centers of active galaxies, glows in infrared radiation. Objects too cool to glow visibly may shine brightly in infrared radiation.

Beginning in 1898, Hale and his colleagues began to measure infrared radiation from celestial bodies. They successfully detected such radiation from Jupiter and Saturn and the stars Vega and Arcturus.

Modern Infrared Research

Yerkes Observatory has maintained a leadership role in the development of instruments for the study of infrared radiation. Yerkes researchers developed instruments for the Kuiper Airborne Observatory (KAO) (1974-1995) and are now working on instruments for SOFIA (Stratospheric Observatory for Infrared Astronomy) (2001-).

Yerkes infrared detectors were carried aloft as attachments to a 36-inch reflector aboard the Kuiper Airborne Observatory (KAO), named in honor of Gerard Kuiper, a former Yerkes Observatory director. The plane, a modified C141-A, was operated by the National Aeronautics and Space Administration (NASA). It cruised at altitudes of up to 45,000 feet where the air is thin and dry enough to permit detection of infrared radiation blocked elsewhere by atmospheric moisture. The KAO was taken out of service in 1995 in order to free up money for the next project, SOFIA.

SOFIA (Stratospheric Observatory for Infrared Astronomy) is a Boeing 747-SP, and it will use a 97-inch (2.5 meter) reflector. It will gather seven times as much infrared radiation as the KAO and provide images that are three times sharper.

The Apache Point Observatory

Yerkes Observatory personnel develop detectors and other instruments for mountaintop observatories where the thinner atmosphere permits better observations. The University of Chicago is a member of the Astrophysical Research Consortium (ARC) which operates such an observatory near Alamogorgo, New Mexico. Here, at the Apache Point Observatory, astronomers use a 3.5-meter telescope to study infrared and visible light.

The innovative 3.5-meter telescope is designed to spare researchers the time and expense of travel to its remote mountaintop location; it can be operated with a computer from any place on Earth that has a computer link. Yerkes faculty, graduate students, and technicians develop instruments to expand the information-gathering capabilities of the telescope.

Map of the Universe

Yerkes researchers are also involved in the Sloan Digital Sky Survey (SDSS), which uses a 2.5-meter telescope at Apache Point. SDSS will survey and measure distances to one million galaxies, providing an accurate, three-dimensional map of the Universe. Data obtained from this vast survey will be processed at Fermilab in Batavia, Illinois.

Other Mountaintop Observatories

Yerkes scientists conduct astrophysical research at several mountaintop locations, employing instruments designed, constructed, and tested at the Observatory for specific telescopes elsewhere.

Yerkes infrared detectors have been used at the Kitt Peak National Observatory 4-meter reflector in Arizona. Similar detectors have been used on Mauna Kea, Hawaii, at the NASA Infrared Telescope Facility and the Caltech Submillimeter Observatory. Instruments are under construction at Yerkes for use on the new 10-meter Keck Telescope. One of the greatest challenges is designing instruments for telescopes at the South Pole, one of the most remote, least hospitable places on Earth.

Astrophysics at the South Pole

Despite the harsh conditions, the South Pole is perhaps the best place on Earth to conduct astrophysical research. Temperatures in summer average 20 degrees below zero Fahrenheit; in the winter they can fall to 125 degrees below zero Fahrenheit. The extreme cold removes water vapor from the air. The dryness and high elevation of the continent (about 10,000 feet above sea level) at the South Pole greatly facilitate observations at visible and infrared wavelengths.

Several instruments for the South Pole were developed here at Yerkes.

Education and Outreach

As part of Yerkes' involvement in the Center for Astrophysical Research in Antarctica (CARA), Chicago high school students learn about astrophysics in a cooperative effort involving Yerkes, other University of Chicago units, George Williams College, and the Adler Planetarium.

The 24-inch here at Yerkes is currently used as part of Hands-On Universe, an NSF-sponsored project whereby middle and high school students can work with real astronomical data.

Go back to the page about the science currently going on at Yerkes Observatory.

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Content originally generated in March 1995.
This file was last modified on 20 April 1999.