Mindblown: a blog about philosophy.

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For Further Exploration Articles Blades, J. C. “Fixing the Hubble One Last Time.” Sky & Telescope (October 2008): 26. On the last Shuttle service mission and what the Hubble was then capable of doing. Brown, A. “How Gaia will Map a Billion Stars.” Astronomy (December 2014): 32. Nice review of the mission to do photometry and spectroscopy of all…

Learning Objectives By the end of this section, you will be able to: If you’ve ever gone on a hike, you have probably been eager to see what lies just around the next bend in the path. Researchers are no different, and astronomers and engineers are working on the technologies that will allow us to…

Learning Objectives By the end of this section, you will be able to: Earth’s atmosphere blocks most radiation at wavelengths shorter than visible light, so we can only make direct ultraviolet, X-ray, and gamma ray observations from space (though indirect gamma ray observations can be made from Earth). Getting above the distorting effects of the…

Learning Objectives By the end of this section, you will be able to: In addition to visible and infrared radiation, radio waves from astronomical objects can also be detected from the surface of Earth. In the early 1930s, Karl G. Jansky, an engineer at Bell Telephone Laboratories, was experimenting with antennas for long-range radio communication when…

Learning Objectives By the end of this section, you will be able to: Since Newton’s time, when the sizes of the mirrors in telescopes were measured in inches, reflecting telescopes have grown ever larger. In 1948, US astronomers built a telescope with a 5-meter (200-inch) diameter mirror on Palomar Mountain in Southern California. It remained…

Learning Objectives By the end of this section, you will be able to: Systems for Measuring Radiation There are three basic components of a modern system for measuring radiation from astronomical sources. First, there is a telescope, which serves as a “bucket” for collecting visible light (or radiation at other wavelengths, as shown in (Figure…

If you look at the sky when you are far away from city lights, there seem to be an overwhelming number of stars up there. In reality, only about 9000 stars are visible to the unaided eye (from both hemispheres of our planet). The light from most stars is so weak that by the time…