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From an NRAO press release, March 9, 2015:

From earthbound optical telescopes, the surface of Venus is shrouded beneath thick clouds made mostly of carbon dioxide. To penetrate this veil, probes like NASA’s Magellan spacecraft use radar to reveal remarkable features of this planet, like mountains, craters, and volcanoes.

Credit: B. Campbell, Smithsonian, et al., NRAO/AUI/NSF, Arecibo

Credit: B. Campbell, Smithsonian, et al., NRAO/AUI/NSF, Arecibo

Recently, by combining the highly sensitive receiving capabilities of the National Science Foundation’s (NSF) Green Bank Telescope (GBT) and the powerful radar transmitter at the NSF’s Arecibo Observatory, astronomers were able to make remarkably detailed images of the surface of this planet without ever leaving Earth. The radar signals from Arecibo passed through both our planet’s atmosphere and the atmosphere of Venus, where they hit the surface and bounced back to be received by the GBT in a process known as bistatic radar.

This capability is essential to study not only the surface as it appears now, but also to monitor it for changes. By comparing images taken at different periods in time, scientists hope to eventually detect signs of active volcanism or other dynamic geologic processes that could reveal clues to Venus’s geologic history and subsurface conditions.

Links: NRAO press release.

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The National Radio Astronomy Observatory has released a new video about the Karl G. Jansky Very Large Array (VLA), narrated by actress Jodie Foster, for their Visitor Center near Socorro, New Mexico. (See Section 3.8d and Section 15.4.)

Credit: Wikipedia

Credit: Wikipedia

Called Beyond the Visible, the 24-minute movie tells the behind-the-scenes story of the operation and scientific achievements of the VLA, which has been at the forefront of astrophysical research since 1980. Spectacular ground and aerial footage of the iconic radio telescope is augmented by first-person interviews with staffers who keep the telescope working and scientists who use it to discover exciting new facts about the Universe. The documentary also depicts many of the technical tasks needed to keep the array functioning at the forefront of science.

Links: The NRAO has made the video available for viewing online here. An earlier movie “Into Deepest Space” tells the story of the Atacama Large Millimeter/submillimeter Array (ALMA).

A strange stellar pair nearly 7,000 light-years from Earth has provided physicists with a unique cosmic laboratory for studying the nature of gravity. The extremely strong gravity of a massive neutron star in orbit with a companion white dwarf star puts competing theories of gravity to a test more stringent than any available before. Once again, Albert Einstein’s General Theory of Relativity, published in 1915, comes out on top.

A newly-discovered pulsar — a spinning neutron star with twice the mass of the Sun — and its white-dwarf companion, orbiting each other once every two and a half hours, has put gravitational theories to the most extreme test yet. Observations of the system, dubbed PSR J0348+0432, produced results consistent with the predictions of General Relativity.

In such a system, the orbits decay and gravitational waves are emitted, carrying energy from the system. By very precisely measuring the time of arrival of the pulsar’s radio pulses over a long period of time, astronomers can determine the rate of decay and the amount of gravitational radiation emitted. The large mass of the neutron star in PSR J0348+0432, the closeness of its orbit with its companion, and the fact that the companion white dwarf is compact but not another neutron star, all make the system an unprecedented opportunity for testing alternative theories of gravity.

Einstein’s predictions were found to hold up quite well, despite the extreme nature of the system. which is good news for researchers hoping to make the first direct detection of gravitational waves.

Credit: Antoniadis, et al.

 

The original NRAO press release may be viewed here.