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Sir Fred Hoyle (24 June 1915 –20 August 2001) was an English astronomer who formulated the theory of stellar nucleosynthesis and was one of the authors of the influential B2FH paper. He also held controversial stances on other scientific matters—in particular his rejection of the "Big Bang" theory (a term coined by him on BBC Radio) in favor of the "steady-state model",and his promotion of panspermia as the origin of life on Earth. He spent most of his working life at St John's College,Cambridge and served as the founding director of the Institute of Theoretical Astronomy at Cambridge.
Venus is the second planet from the Sun. It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth. Venus has by far the densest atmosphere of the terrestrial planets,composed mostly of carbon dioxide with a thick,global sulfuric acid cloud cover. At the surface it has a mean temperature of 737 K and a pressure 92 times that of Earth's at sea level. These extreme conditions compress carbon dioxide into a supercritical state at Venus's surface.
A terrestrial planet,telluric planet,or rocky planet,is a planet that is composed primarily of silicate,rocks or metals. Within the Solar System,the terrestrial planets accepted by the IAU are the inner planets closest to the Sun:Mercury,Venus,Earth and Mars. Among astronomers who use the geophysical definition of a planet,two or three planetary-mass satellites –Earth's Moon,Io,and sometimes Europa –may also be considered terrestrial planets. The large rocky asteroids Pallas and Vesta are sometimes included as well,albeit rarely. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth,as these planets are,in terms of structure,Earth-like. Terrestrial planets are generally studied by geologists,astronomers,and geophysicists.
Phosphine (IUPAC name:phosphane) is a colorless,flammable,highly toxic compound with the chemical formula PH3,classed as a pnictogen hydride. Pure phosphine is odorless,but technical grade samples have a highly unpleasant odor like rotting fish,due to the presence of substituted phosphine and diphosphane (P2H4). With traces of P2H4 present,PH3 is spontaneously flammable in air (pyrophoric),burning with a luminous flame. Phosphine is a highly toxic respiratory poison,and is immediately dangerous to life or health at 50 ppm. Phosphine has a trigonal pyramidal structure.
The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile,which observe electromagnetic radiation at millimeter and submillimeter wavelengths. The array has been constructed on the 5,000 m (16,000 ft) elevation Chajnantor plateau –near the Llano de Chajnantor Observatory and the Atacama Pathfinder Experiment. This location was chosen for its high elevation and low humidity,factors which are crucial to reduce noise and decrease signal attenuation due to Earth's atmosphere. ALMA provides insight on star birth during the early Stelliferous era and detailed imaging of local star and planet formation.
A transit of Venus takes place when Venus passes directly between the Sun and the Earth,becoming visible against the solar disk. During a transit,Venus is visible as a small black circle moving across the face of the Sun.
The James Clerk Maxwell Telescope (JCMT) is a submillimetre-wavelength radio telescope at Mauna Kea Observatory in Hawaii,US. The telescope is near the summit of Mauna Kea at 13,425 feet (4,092 m). Its primary mirror is 15 metres across:it is the largest single-dish telescope that operates in submillimetre wavelengths of the electromagnetic spectrum. Scientists use it to study the Solar System,interstellar dust and gas,and distant galaxies.
The Black Cloud is a 1957 science fiction novel by British astrophysicist Fred Hoyle. It details the arrival of an enormous cloud of gas that enters the Solar System and appears about to destroy most of the life on Earth by blocking the Sun's radiation.
Observations of the planet Venus include those in antiquity,telescopic observations,and from visiting spacecraft. Spacecraft have performed various flybys,orbits,and landings on Venus,including balloon probes that floated in the atmosphere of Venus. Study of the planet is aided by its relatively close proximity to the Earth,compared to other planets,but the surface of Venus is obscured by an atmosphere opaque to visible light.
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Sara Seager is a Canadian-American astronomer and planetary scientist. She is a professor at the Massachusetts Institute of Technology and is known for her work on extrasolar planets and their atmospheres. She is the author of two textbooks on these topics,and has been recognized for her research by Popular Science,Discover Magazine,Nature,and TIME Magazine. Seager was awarded a MacArthur Fellowship in 2013 citing her theoretical work on detecting chemical signatures on exoplanet atmospheres and developing low-cost space observatories to observe planetary transits.
The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System. It has a surface that is 90% basalt,and about 65% of the planet consists of a mosaic of volcanic lava plains,indicating that volcanism played a major role in shaping its surface. There are more than 1,000 volcanic structures and possible periodic resurfacing of Venus by floods of lava. The planet may have had a major global resurfacing event about 500 million years ago,from what scientists can tell from the density of impact craters on the surface. Venus has an atmosphere rich in carbon dioxide,with a pressure that is 90 times that of Earth's atmosphere.
The history of scientific thought about the formation and evolution of the Solar System began with the Copernican Revolution. The first recorded use of the term "Solar System" dates from 1704. Since the seventeenth century,philosophers and scientists have been forming hypotheses concerning the origins of the Solar System and the Moon and attempting to predict how the Solar System would change in the future. RenéDescartes was the first to hypothesize on the beginning of the Solar System;however,more scientists joined the discussion in the eighteenth century,forming the groundwork for later hypotheses on the topic. Later,particularly in the twentieth century,a variety of hypotheses began to build up,including the now–commonly accepted nebular hypothesis.
The possibility of life on Venus is a subject of interest in astrobiology due to Venus' proximity and similarities to Earth. To date,no definitive evidence has been found of past or present life there. In the early 1960s,studies conducted via spacecraft demonstrated that the current Venusian environment is extreme compared to Earth's. Studies continue to question whether life could have existed on the planet's surface before a runaway greenhouse effect took hold,and whether a relict biosphere could persist high in the modern Venusian atmosphere.
Water activity (aw) is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. In the field of food science,the standard state is most often defined as pure water at the same temperature. Using this particular definition,pure distilled water has a water activity of exactly one. Water activity is the thermodynamic activity of water as solvent and the relative humidity of the surrounding air after equilibration. As temperature increases,aw typically increases,except in some products with crystalline salt or sugar.
An Earth analog,also called an Earth analogue,Earth twin,or second Earth,is a planet or moon with environmental conditions similar to those found on Earth. The term Earth-like planet is also used,but this term may refer to any terrestrial planet.
Victoria Suzanne Meadows is a Professor with the Astronomy Department and Director of the Astrobiology Program at the University of Washington. She is also the Principal Investigator for the NASA Astrobiology Institute's Virtual Planetary Laboratory Lead Team and the chair of the NAI Focus Group on Habitability and Astronomical Biosignatures (HAB). The research direction of the team is to create computer models that can be used to understand planet formation,stability and orbital evolution,and to simulate the environment and spectra of planets that can potentially be habitable.
The Fred Hoyle Medal and Prize was established in 2008 by the Institute of Physics of London for distinguished contributions to astrophysics,gravitational physics or cosmology. The medal is named after astronomer Fred Hoyle who formulated the theory of stellar nucleosynthesis. The medal is made of silver and accompanied by a prize and a certificate. The medal was awarded biennially from 2008 to 2016. It has been awarded annually since 2017.
Sarah Rugheimer is a Swiss-American astrobiologist and astrophysicist at Jesus College,Oxford. Her research focuses on the atmospheric composition of exoplanets,and ways of detecting life.
Clara Sousa-Silva is a research scientist at Center for Astrophysics | Harvard &Smithsonian. Sousa-Silva is an expert on phosphine. She has contributed to investigations of the possibility of life on Venus,working with Jane Greaves and others. Sousa-Silva also directs the Harvard-MIT Student Research Mentoring Program,which pairs high school students with astronomers to conduct research.
References
- ↑ Rincon, Paul (2 April 2008). "Astronomers see 'youngest planet'". BBC News . Retrieved 3 July 2017.
- Highfield, Roger (2 April 2008). "Baby planet found around star HL Tau". Daily Telegraph . Retrieved 3 July 2017. - ↑ "Fred Hoyle Medal and Prize recipients". Awards. Institute of Physics . Retrieved 15 September 2020.
- ↑ "Paucity of phosphorus hints at precarious path for extraterrestrial life". Phys.org . 4 April 2018. Retrieved 5 April 2018.
- "Alien life may be more unlikely than previously thought, according to new study". The Daily Telegraph . 5 April 2018. Retrieved 5 April 2018. - ↑ Perkins, Sid (14 September 2020). "'Curious and unexplained.' Gas spotted in Venus's atmosphere is also spewed by microbes on Earth". Science . Retrieved 14 September 2020.
- ↑ Chang, Kenneth; Stirone, Shannon (22 June 2021). "Life on Venus? The Picture Gets Cloudier". New York Times. Retrieved 6 March 2022.
