Question

The value of radio and infrared astronomy is partly based on the fact that light at these wavelengths can travel through cosmic clouds of gas and dust without being absorbed. That means astronomers can observe phenomena in our Galaxy and in other galaxies that otherwise would be hidden from view at optical and shorter wavelengths. Radio emission at centimeter-to-meter wavelengths can be effectively observed from the ground. What are other unique characteristics of radio astronomy within this wavelength range?

Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

1. At these wavelengths, it is necessary to build telescopes with very large light-collecting ______ to obtain maps of sufficient sensitivity to faint cosmic signals.
2. At these wavelengths, it is necessary to build telescopes with very large signal-sensing ______ to obtain maps of sufficient detail.
3. Radio astronomers have pioneered the use of multiple telescopes working in concert that can produce maps of radio emission as detailed as optical images. These arrays of multiple telescopes are known as ______.
4. Astronomical observations at these wavelengths can be obtained even during ______.

WORD BANK
- interferometers
- storms
- areas
- baselines

Answer 1

1. Areas
2. Baselines
3. Interferometers
4. Storms

Radio astronomy involves observations of celestial sources with large ground-based telescopes. The large collecting areas ensure that enough of the weak radio signal is received and registered. Large signal-sensing baselines are necessary to achieve adequate resolving power at these long wavelengths. The largest baselines (and highest angular resolutions) are achieved by combining the signals from several individual telescopes that are arranged in an interferometric array spanning hundreds to thousands of meters. Radio observations are important because they bring us unique information about cosmic objects that otherwise would be invisible, such as radio galaxies and the active heart of our own Milky Way galaxy. Moreover, radio astronomical observations can be obtained from the ground even during inclement weather.