Planetary scientist in the context of "Micrometeoroid"

A planetary-mass moon is a planetary-mass object that is a natural satellite of another non-stellar celestial object. Because of their mass, these moons are large and ellipsoidal (sometimes spherical) in shape due to hydrostatic equilibrium caused by internal partial melting and differentiation and/or from tidal or radiogenic heating, in some cases forming a subsurface ocean.

Planetary-mass moons are sometimes called satellite planets by some planetary scientists such as Alan Stern, who are more concerned with whether a celestial body has planetary geology (that is, whether it is a planetary body) than its solar or non-solar orbit (planetary dynamics). Thus they consider planetary-mass moons to be a subset of the planets. This conceptualization of planets as three classes of objects (classical planets, dwarf planets and satellite planets) has not been accepted by the International Astronomical Union (the IAU).

Carl Edward Sagan (/ˈseɪɡən/; SAY-gən; November 9, 1934 – December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by exposure to light. He assembled the first physical messages sent into space, the Pioneer plaque and the Voyager Golden Record, which are universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. He argued in favor of the hypothesis, which has since been accepted, that the high surface temperatures of Venus are the result of the greenhouse effect.

Initially an assistant professor at Harvard, Sagan later moved to Cornell University, where he spent most of his career. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He wrote many popular science books, such as The Dragons of Eden, Broca's Brain, Pale Blue Dot and The Demon-Haunted World. He also co-wrote and narrated the award-winning 1980 television series Cosmos: A Personal Voyage, which became the most widely watched series in the history of American public television: Cosmos has been seen by at least 500 million people in 60 countries. A book, also called Cosmos, was published to accompany the series. Sagan also wrote a science-fiction novel, published in 1985, called Contact, which became the basis for the 1997 film of the same name. His papers, comprising 595,000 items, are archived in the Library of Congress.

Megan E. Schwamb (born 1984) is an American astronomer and planetary scientist, and lecturer at Queen's University, Belfast. Schwamb has discovered and co-discovered several trans-Neptunian objects, and is involved with Citizen science projects such as Planet Four and Planet Hunters.

Gerard Peter Kuiper (/ˈkaɪpər/ KY-pər; born Gerrit Pieter Kuiper, Dutch: [ˈɣɛrɪt ˈpitər ˈkœypər]; 7 December 1905 – 23 December 1973) was a Dutch astronomer, planetary scientist, selenographer, author and professor. The Kuiper belt is named after him.

Kuiper is considered by many to be the father of modern planetary science.

The Day the Earth Smiled is a composite photograph taken by the NASA spacecraft Cassini on July 19, 2013. During an eclipse of the Sun, the spacecraft turned to image Saturn and most of its visible ring system, as well as Earth and the Moon as distant pale dots. The spacecraft had twice taken similar photographs (in 2006 and 2012) in its previous nine years in orbit around the planet. The name also refers to the activities associated with the event, as well as to the photographic mosaic created from it.

Conceived by the planetary scientist Carolyn Porco, the imaging team leader for Cassini, the concept called for the people of the world to reflect on their place in the universe, to marvel at life on Earth, and, at the time the pictures were taken, to look up and smile in celebration.

Richard Stothers was an astronomer and planetary scientist with the Goddard Institute for Space Studies, which he joined in June 1961 as a graduate student. Within two years, he had received his Ph.D. from Harvard and became a permanent staff member of the institute, where he spent the remainder of his career. He contributed to the modern understanding of the origin and evolution of stars and, later in life, to climate science. He was able to read original papers in several languages, which allowed him to extract information on historical climate change from ancient writings. Stothers also examined ancient reports of unidentified flying objects and examined the factual basis for myths of "giant serpents".

Stothers was raised in New York and graduated from Phillips Exeter Academy. He was a member of the Cum Laude Society. He attended college at Princeton, where he was a member of the fencing team, and majored in mathematics. His thesis was entitled “The Problem of Pulsating Stellar Models.”

Eberhard Grün (born 30 March 1942, in Germany) is a German planetary scientist who specialized in cosmic dust research. He is an active emeritus at the Max Planck Institute for Nuclear Physics (MPIK), Heidelberg (Germany), research associate at the Laboratory for Atmospheric and Space Physics (LASP) in Boulder (Colorado), and was a professor at the University of Heidelberg until his retirement in 2007. Eberhard Grün has had a leading role in international cosmic dust science for over 40 years.