astronomy

Ejnar Hertzsprung and the Hertzsprung-Russell Diagram

Ejnar Hertzsprung and the Hertzsprung-Russell Diagram

On October 8, 1873, Danish chemist and astronomer Ejnar Hertzsprung was born. Together with Henry Norris Russell, Hertzsprung developed the Hertzsprung–Russell diagram, a scatter graph of stars showing the relationship between the stars‘ absolute magnitudes or luminosities versus their spectral classifications or effective temperatures, which has become fundamental to the study of stellar evolution. Ejnar Hertzsprung was probably not formally educated, but studied in technological colleges in Denmark and became a…
ALMA – the largest and most expensive ground-based astronomical project

ALMA – the largest and most expensive ground-based astronomical project

On October 3, 2011, first images produced by the Atacama Large Millimeter Array were released to the press. The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of radio telescopes in the Atacama desert of northern Chile. ALMA is currently the largest and most expensive ground-based astronomical project, costing between US$1.4 and 1.5 billion. ALMA is an interferometer, i.e. ,amy small radio telescopes working together as a single large…
Sir Martin Ryle and Radio Astronomy

Sir Martin Ryle and Radio Astronomy

On September 27, 1918, English radio astronomer and Nobel Laureate Sir Martin Ryle was born. Ryle developed revolutionary radio telescope systems and used them for accurate location and imaging of weak radio sources. He was Astronomer Royal from 1972 to 1982 and shared the Nobel Prize in Physics in 1974 with Antony Hewish, the first Nobel prize awarded in recognition of astronomical research. Martin Ryle was the son of Professor John Alfred Ryle…
The first Observation of Gravitational Waves

The first Observation of Gravitational Waves

On September 14, 2015, the LIGO Scientific Collaboration observed gravitational waves from a 410 megaparsec (1.3 billion light years) distant merger of two black holes. Previously, gravitational waves had only been inferred only indirectly, via their effect on the timing of pulsars in binary star systems. It was also the first observation of a binary black hole merger, demonstrating both the existence of binary stellar-mass black hole systens, and the…
Leonid Kulik and the Tunguska Event

Leonid Kulik and the Tunguska Event

On August 19, 1883, Russian mineralogist Leonid Alekseyevich Kulik was born. Kulik is noted for his research in meteorites. In 1927, Kulik conducted the first scientific expedition (for which records survive) to study the Tunguska meteor impact site, the largest impact event in recorded history, which had occurred on 30 June 1908.[1] Leonid Kulik was born in Tartu, Estonia, which was later to become part of the Soviet Union, and was…
Jerry R. Ehman and the Wow! Signal

Jerry R. Ehman and the Wow! Signal

On August 15, 1977, a strong narrowband radio signal was received by the Big Ear radio telescope of the Ohio State University, United States, then assigned to a SETI project. Astronomer Jerry R. Ehman discovered the signal a few days later, while reviewing the recorded data and was so impressed that he circled the reading on the computer printout and wrote the comment Wow! on its side. Jerry R. Ehman…
Helen Hogg and the Globular Clusters

Helen Hogg and the Globular Clusters

On August 1, 1905, American-Canadian astronomer Helen Battles Sawyer Hogg was born. Hogg is noted for pioneering research into globular clusters (stars with cyclical changes of brightness found within huge, dense conglomerations of stars located in the outer halo of the Milky Way galaxy) and variable stars. She was the first female president of several astronomical organizations and a notable woman of science in a time when many universities would…
The Gran Telescopio Canarias

The Gran Telescopio Canarias

On July 14, 2007, the Gran Telescopio Canarias saw first light, also known as the Great Canary Telescope (GTC), located at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain. With an aperture of 10.4m, as of 2015, it is the world’s largest single-aperture optical telescope. It has a segmented mirror, i.e. an array of smaller mirrors designed to act as segments of…
Jérôme Lalande measuring the distance to the Moon

Jérôme Lalande measuring the distance to the Moon

On July 11, 1732, French astronomer, freemason and writer Jérôme Lalande was born. Lalande is best known for having determined the Moon’s parallax from Berlin for the French Academy in 1751. His planetary tables, into which he introduced corrections for mutual perturbations, were the best available up to the end of the 18th century. Jérôme Lalande first studied at the Jesuit College in Lyon and later went to Paris to…
George Ellery Hale and the Magnetic Fields in Sunspots

George Ellery Hale and the Magnetic Fields in Sunspots

On June 29, 1868, American solar astronomer George Ellery Hale was born. He is best known for his discovery of magnetic fields in sunspots, and as the leader or key figure in the planning or construction of several world-leading telescopes, including the 200-inch Hale reflecting telescope at Palomar Observatory. George Ellery Hale was the oldest of three children  and it is believed that he was highly supported by his parents…
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