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What is a Planet? (Space Place, NASA)

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Physical Realm
Universe Astronomical Instrument
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

Resources

These are organized by a classification scheme developed exclusively for Cosma. More…

General

Portal

Planets & Planetary Systems Internet Resources (Library of Congress)

Dictionary

planet : any of the large bodies that revolve around a star — Webster

OneLook, Free Dictionary, Wiktionary, Urban Dictionary

Thesaurus

Roget’s II (Thesaurus.com), Merriam-Webster Thesaurus, Visuwords

Encyclopedia

Planet is an astronomical body orbiting a star or stellar remnant that

is massive enough to be rounded by its own gravity,
is not massive enough to cause thermonuclear fusion, and
has cleared its neighbouring region of planetesimals.

The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit. Although eight of the planetary bodies discovered before 1950 remain “planets” under the modern definition, some celestial bodies, such as Ceres, Pallas, Juno and Vesta (each an object in the solar asteroid belt), and Pluto (the first trans-Neptunian object discovered), that were once considered planets by the scientific community, are no longer viewed as such. — Wikipedia

Dwarf planet is a planetary-mass object that is neither a true planet nor a natural satellite. That is, it is in direct orbit of a star, and is massive enough for its gravity to compress it into a hydrostatically equilibrious shape (usually a spheroid), but has not cleared the neighborhood of other material around its orbit. The term was adopted in 2006 as part of a three-way categorization of bodies orbiting the Sun, brought about by an increase in discoveries of objects farther away from the Sun than Neptune that rivaled Pluto in size, and finally precipitated by the discovery of an even more massive object, Eris. — Wikipedia

Planets (Eric Weisstein’s World of Astronomy, Wolfram Research)
David Darling’s Internet Encyclopedia of Science
Encyclopædia Britannica

Search

Planets (Wolfram Alpha)

Science

Planetary science or, more rarely, planetology, is the scientific study of planets (including Earth), moons, and planetary systems and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science, but which now incorporates many disciplines, including planetary geology (together with geochemistry and geophysics), cosmochemistry, atmospheric science, oceanography, hydrology, theoretical planetary science, glaciology, and exoplanetology. Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology. — Wikipedia

Planetary Science (NASA/JPL)

Exoplanet or extrasolar planet is a planet outside the Sun’s solar system. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such. However, the first scientific detection of an exoplanet was in 1988, although it was not confirmed to be an exoplanet until later in 2012. The first confirmed detection occurred in 1992. As of September 2018, there are 3,823 confirmed planets in 2,860 systems, with 632 systems having more than one planet. — Wikipedia

Exoplanet Exploration: Planets Beyond Our Solar System (NASA)
Exoplanet Data Explorer (Exoplanet.org)
What Is an Exoplanet? (Space Place, NASA)
Extrasolar Planets (Ask an Astronomer, Cornell University)
Extrasolar Systems Internet Resources (Library of Congress)
Extrasolar Systems Internet Resources (Library of Congress)
Extrasolar Planets (Eric Weisstein’s World of Astronomy, Wolfram Research)
Exoplanets (Wolfram Alpha)

Preservation

History

400 years, 7,500 words: A history of planetary science (Lauren Gold, Cornell Chronicle)

Quotation

Quotations Page

Library

WorldCat, Library of Congress, UPenn Online Books, Open Library

Participation

Education

Planets and Dwarf Planets (Ask an Astronomer, Cornell University)

Course

Crash Course Astronomy (YouTube)

Physics and Chemistry of the Terrestrial Planets (MIT)
OER Commons: Open Educational Resources

Community

Organization

International Astronomical Union (IAU)
Minor Planet Center (International Astronomical Union)
The Planetary Society

News

Science News, AAAS EurekaAlert, Phys.org, NPR Archives

Book

ISBNdb

Government

NASA Planetary Science

Document

USA.gov

Expression

Poem

OEDILF: The Omnificent English Dictionary In Limerick Form

Music

Song Lyrics

More…

Posts on Cosma

• Moon’scapes (2/28/2020) - There’s no denying that it’s been a rough week for many Earthlings. On the other hand, it’s been a great week for anyone who spends their time more preoccupied with the Moon than with more earthly concerns. That’s because there’s a treasure trove of news about our lunar realm. For example, NASA’s Goddard Media Studios … Continue reading Moon’scapes
• Lunar Landings (7/19/2019) - Saturday, July 20th is the 50th anniversary of the Apollo 11 Moon Landing, and there’s a massive media blitz surrounding the occasion. Pretty much every major news outlet is covering it in some way, and it’s no surprise that NASA is leading the publicity frenzy. On Friday at 1 p.m. (EDT) NASA is broadcasting 50 … Continue reading Lunar Landings
• Save the babies! (4/20/2019) - Monday, April 22 is Earth Day, and this year’s campaign theme is Protect our Species. Here’s a one minute promo from Defenders of Wildlife featuring a few endangered species. Here’s another one minute video that features a different group of species that are in danger. It struck me that, while those videos are heart wrenching, … Continue reading Save the babies!
• Speleological Wonders (2/8/2019) - A few days ago I came across this short 360° video from the The New York Times about how biologist Naowarat Cheeptham has been searching for antibiotics in a cave. It’s an interesting story, and there’s a lot more about it in this article from Wired. Inside the slimy underground hunt for humanity’s antibiotic saviour … Continue reading Speleological Wonders
• Mars is hard! (11/25/2018) - Update 8:30 PM November 26, 2018 (EST) Touchdown! Mars InSight lander reaches red planet (Alexandra Witze, Nature) NASA’s InSight Mission Triumphantly Touches Down on Mars (Ian O’Neill, Scientific American) InSight has landed with Updates (Emily Lakdawalla, Planetary Society) Landing Replay (SciNews) Original Post If you hear a phrase like “six and a half minutes of … Continue reading Mars is hard!
• Cosma’s Virtual Zoo (11/22/2018) - I’ve been updating the pages on Cosma related to nature for quite awhile. It’s been lots of fun, and I must confess that it probably took longer than it should have. That’s because there are a ridiculous number of great animal videos on YouTube — no surprise, the growing cache of 360° videos are particularly … Continue reading Cosma’s Virtual Zoo
• Get Lost in Space! (9/14/2018) - Way back in August, in anticipation of the start of a new school year, I set out to update the pages on this site related to space. Those pages tend to be popular among the teachers and students who use Cosma, and I happen to enjoy updating them, too. It sounded like a short, fun … Continue reading Get Lost in Space!
• Milky Way Lost & Found (8/15/2018) - Have you seen the Milky Way? You may think that you have, but are you sure? Unless you live in an extremely remote area, or you’ve visited one, then you probably haven’t seen our own galaxy, the Milky Way, very well, or at all. Worse yet, you may not even realize that it’s missing. The … Continue reading Milky Way Lost & Found
• Visioning Spacesteads (8/8/2018) - Space, the final frontier… Humans have been imagining what it would be like to setup homesteads and live in space for about as long as they’ve been imagining how to get there, but the process didn’t really take off until after we actually got there. Back in the 1970’s NASA dedicated some resources to the … Continue reading Visioning Spacesteads
• Exoplanet Junket (6/2/2018) - I’m on a vacation of sorts, so it’s no surprise that stories about travel tend to catch my eye. However, it is surprising if the story happens to be about something that NASA’s done. This week NASA released a new project that they’ve dubbed the Exoplanet Travel Bureau. The core of the project consists of … Continue reading Exoplanet Junket
• Octopuses from Space! (5/20/2018) - Did you hear the one about the octopuses from space? It sounds like the title of a cheesy sci-fi movie, doesn’t it? But it isn’t, this time, or at least, yet. Instead, it’s actually an oddball theory that’s been put forth in a recently published “scientific” article that’s getting quite a lot of buzz in … Continue reading Octopuses from Space!
• Arbornautics (5/7/2018) - Traditional news stories usually cover a single subject or the straightforward relationship between two subjects. However, every once in awhile, a story comes along that crams a deceptive number of subjects and interesting relationships into a tiny space. Exploring stories like that can be an adventure. Here’s a wonderful, five minute clip from Seeker that’s … Continue reading Arbornautics
• Yellowstone, Beauty & Beast (4/30/2018) - If you have been Yellowstone National Park, then you know it is a vast, beautiful place with some fairly odd geologic features that smell bad, like rotten eggs. If you’ve never been there, then you might just have a fairly apocalyptic view of it because of the supervolcano under it that has been featured in … Continue reading Yellowstone, Beauty & Beast
• Great Views of Earth (4/22/2018) - April 22nd is Earth Day! In honor of that, here are some great ways to see the honoree. First, you can get a nice view from this neat 360° Video from Seeker. It essentially shows you what it would feel like if you could just fly straight up and see the Earth from space. National … Continue reading Great Views of Earth
• Perspectives on Earth (11/23/2017) - Last week NASA released this fascinating video entitled Our Living Planet based upon 20 years of data from satellites that observe all plant life at the surface of the land and ocean. You can find out more about the video from this article. The Changing Colors of our Living Planet (NASA) Of course, releasing fantastic … Continue reading Perspectives on Earth
• Around the world in… (10/27/2017) - Once upon a time, way back in the Victorian era a hundred years ago when Jules Verne was writing Around the World in Eighty Days, it took a little while to even vicariously circumnavigate the world by reading about it. These days, thanks to professional video productions from groups like Travel Channel and Lonely Planet, … Continue reading Around the world in…
• NASA’s Excellent Adventures (9/13/2017) - NOTE: This post was updated on the morning of September 15th, see new videos below. NASA is always up to something fascinating. There are so many milestones and discoveries, it’s hard to resist featuring them in every post. However, there are a few events that definitely deserve special attention right now. First, August 20th and … Continue reading NASA’s Excellent Adventures
• Umbraphiles (8/20/2017) - umbraphile : One who loves eclipses, often travelling to see them. — Wiktionary Yes, this is that obligatory post about “The Solar Eclipse” (NASA, Wikipedia). Of course, there had to be one — eclipses really are just too cool to ignore. You’ve already been bombarded with explanations of the science and history of eclipses, but … Continue reading Umbraphiles
• Ring o’ Fire, South (8/15/2017) - Song titles and colloquial terminology aside, you probably have an idea of what scientists mean when they talk about the “Ring of Fire” (National Geographic, Wikipedia). However, even if you do, a bit of review will be useful for this post. Here’s an imaginative 360° Video that provides a top-level introduction. Here’s a more mundane, … Continue reading Ring o’ Fire, South
• Moon+H2O=Moonbase? (7/25/2017) - One of the big science stories in the news right now is that Earth’s Moon has more water than scientists expected. This Newsy video is just one of the hundreds of stories flooding news feeds. This round of stories has been inspired by this article in Nature Geoscience. Remote detection of widespread indigenous water in … Continue reading Moon+H2O=Moonbase?
• Big Berg Born (7/12/2017) - It’s been about nine months since NASA’s IceBridge mission photographed a rift in the Antarctic Peninsula’s Larsen C ice shelf and predicted the imminent birth of a 2,200 square mile, trillion ton iceberg (technically known as “calving“). The media have been reporting on the story ever since, and it’s been interesting to watch the size … Continue reading Big Berg Born
• Twisters! (6/26/2017) - It’s that time of year when tornadoes tend to make the news. For example, did you see the picture of the guy mowing his lawn during a tornado a few weeks ago? He claimed it wasn’t as bad as it looked, but still… Then there was also this 360° Video of a supercell taken by … Continue reading Twisters!
• Doomed? (5/24/2017) - If you’ve been keeping up the slew of dark headlines in the news this week, then you may have seen some stories about how the Svalbard Global “Doomsday” Seed Vault is doomed, or not, according to which story you read. There were some alarmist headlines, but most of the stories were less drastic, while still … Continue reading Doomed?
• Cassini’s Finale (5/1/2017) - The Cassini space probe has got a serious date with Saturn coming up in the Fall on September 15th, but she’s got a very busy schedule between now and then making a series of dives through the space between Saturn and its rings. The first dive of took place last week (Wednesday, April 26th). Here’s … Continue reading Cassini’s Finale
• Old Maps, New Ways (3/27/2017) - Here is an interesting story about a “3D virtual tour” of the Leventhal Map Center at the Boston Public Library. Boston Public Library map center adds virtual tour (Steve Annear, Boston Globe) Since the Leventhal Map Center isn’t widely known to the general public, here are a couple of videos about it. The “3D tour” … Continue reading Old Maps, New Ways
• TRAPPIST-1 (2/23/2017) - You’ve probably heard that NASA has found a trove of “Earth-like” planets circling the TRAPPIST-1 system roughly 40 light years away, but just in case you haven’t, here’s a short 2 minute AP video about the discovery. Here’s another video from NASA/JPL with more explanation. Most entertainingly, here’s a 360° YouTube Video published by NASA/JPL … Continue reading TRAPPIST-1
• Planet Earth II (1/30/2017) - One interesting thing that’s been happening recently is that some television shows are being released with 360º features to go along with them. For example, the BBC created a lovely set of six 360º videos to coincide with episodes in their Planet Earth II (BBC) series. In case you haven’t been watching, the new Planet … Continue reading Planet Earth II
• Virtual Earth (12/4/2016) - Google has just expanded their pantheon of tools to see the World. This time they have created a tool that allows you to browse the Earth in an interactive 360° format. This is designed to work with HTC’s Vive VR Headset, but you can get a fun sense of the experience with this 360° YouTube … Continue reading Virtual Earth
• Mars 3D (11/16/2016) - Mars is getting even more attention than usual this week, and that is “mostly” because National Geographic began airing their special six part Mars series on Monday nights (9/8c). Here’s a trailer and links about it… Virtual Trip to Mars Offers Ultimate Preview to Crewed Mission (Nadia Drake, National Geographic) Inside Nat Geo’s Incredible Documentary … Continue reading Mars 3D
• ExoMars (10/19/2016) - Oct. 21 Update: Unfortunately, the ExoMars mission’s Schiaparelli lander did not make a successful landing due to technical difficulties, and the crash site has been found. Happily, the mother ship did successfully enter orbit. Why Schiaparelli Probe’s Mars ‘Crash Land’ Is No Failure (Mason Peck, Newsweek) Mars Reconnaissance Orbiter views Schiaparelli landing site (ESA) Here’s … Continue reading ExoMars

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