Sources

Mount Everest vs Mariana Trench

Oct 10 · 1:02 · Ocean

• Mount Everest's summit is 8,849 m above sea level.Al Jazeera, 8 Dec 2020
• The Challenger Deep is about 10,935 m deep.Greenaway et al. 2021, Deep Sea Research I (NOAA repository)
• The Eiffel Tower has been 330 m tall since 2022.KTVU / Associated Press
• No sunlight is left below about 1,000 m.NOAA Ocean Service
• About 3 in 4 animals filmed down to 4,000 m make light.Martini & Haddock 2017, Scientific Reports
• A Cuvier's beaked whale dove to 2,992 m on one breath.Schorr et al. 2014, PLoS ONE
• Every 10 m of seawater adds about one atmosphere of pressure.NOAA Office of Marine and Aviation Operations
• Every crewed visit to the Challenger Deep has been in a deep diving submersible (Trieste 1960, Deepsea Challenger 2012, Limiting Factor from 2019, Fendouzhe from 2020).Wikipedia, List of people who descended to Challenger Deep

What Happens to Your Body at the Bottom of the Ocean?

Oct 9 · 1:04 · Ocean

• Every 10 m of seawater adds one atmosphere of pressure.NOAA Office of Marine and Aviation Operations
• At 10 m deep, a lungful of air shrinks to half.NOAA Office of Marine and Aviation Operations
• The official no limits freedive record is 214 m.Guinness World Records
• The Challenger Deep is about 10,935 m deep.Greenaway et al. 2021, Deep Sea Research I (NOAA repository)
• Foam cups sent 2,500 m down came back shrunken.NOAA Okeanos Explorer, 2017
• Foam is mostly air, so deep sea pressure shrinks foam cups.Live Science
• No fish has been found below about 8,400 m.Yancey et al. 2014, PNAS

How Deep Is the Ocean, Really?

Oct 8 · 1:02 · Ocean

• Red light fades first in seawater, and blue reaches deepest.NOAA Ocean Exploration, Light and Color fact sheet
• Below about 1,000 m, no sunlight reaches the ocean.NOAA JetStream, Layers of the Ocean
• Clear seawater dims light by a fixed share every meter.Morel et al. 2007, Limnology and Oceanography
• The ocean averages 3,682 m deep, a little under 4 km.Charette & Smith 2010, Oceanography
• The Challenger Deep is about 10,935 m deep.Greenaway et al. 2021, Deep Sea Research I (NOAA repository)
• Mariana snailfish usually live 7,000 to 8,000 m down.FishBase
• Even in clear tropical water, only about 1% of visible light, mostly blue, reaches 100 m.University of Hawaiʻi, Exploring Our Fluid Earth, Light in the Ocean
• The Mariana snailfish, described in Zootaxa in 2017, was the deepest fish ever collected from the ocean floor.University of Hawaiʻi News, 2017

We Searched the Universe for a Safer Planet Than Earth

Oct 7 · 11 min · Space

• When it starts to die, the Sun will expand into a red giant and engulf Mercury and Venus, and possibly Earth; its surface is about 10,000 °F (5,500 °C).NASA, Sun facts
• Earth will not be able to escape engulfment when the Sun is a red giant, about 7.59 billion years from now.Schröder & Smith 2008, Monthly Notices of the RAS
• The Sun's main sequence life ends in about 5 billion years and it becomes a red giant; the oceans are lost in about 1 to 1.5 billion years; a runaway greenhouse comes in about 3 to 4 billion; Mercury and Venus are engulfed about 7.6 billion years from now; Earth's engulfment remains uncertain.Wikipedia, Future of Earth
• Earth may survive the Sun's red giant phase.Space.com, Earth may survive the Sun's death
• The Sun brightens about 10% every billion years; in about a billion years it gets hot enough to lose the oceans, with water escaping as hydrogen and oxygen.Jillian Scudder, The Conversation
• Fewer atoms in the core mean it shrinks and heats, so the Sun shines brighter.Phil Plait, Scientific American, 2026
• The Sun fuses hydrogen into helium in its core.EUROfusion, Fusion on the Sun
• Every second, the Sun turns about 600 million tonnes of hydrogen into helium.ITER, What is fusion
• The inner core is a solid iron and nickel sphere with a radius of 1,221 km, up to 9,800 °F; the molten core gives rise to the magnetic field; the solar wind distorts the field into a teardrop shape.NASA, Earth facts
• Earth's radius is 6,371 km (3,959 miles).NASA NSSDC, Earth fact sheet
• The mantle is solid rock that flows at about the rate fingernails grow.USGS, Are tectonic plates floating on magma?
• Moving liquid iron in the outer core generates Earth's magnetic field.USGS, How does the Earth's core generate a magnetic field?
• Earth's magnetosphere shields us from the solar wind and from erosion of the atmosphere.NASA, Earth's magnetosphere
• Earth's magnetosphere deflects the solar wind.NOAA Space Weather Prediction Center, Earth's magnetosphere
• Earth's magnetic field guides electrons so the aurora forms two ovals around the magnetic poles.NOAA Space Weather Prediction Center, Aurora
• Energy and particles travel down field lines near the poles; oxygen gives off green and red light.NASA Space Place, What is an aurora?
• The solar wind is a constant stream of charged particles.NASA, What is the solar wind?
• Each F1 engine's turbopump moved 42,500 gallons of propellant a minute (about 13 tons a second for five engines).Smithsonian National Air and Space Museum, F1 engine
• The space station orbits Earth about every 90 minutes at about five miles per second.NASA, Space station facts and figures
• The station's altitude drops over time due to atmospheric drag; periodic reboosts correct it.NASA JSC, Space Station Orbit Tutorial
• Mars's surface pressure is 6.36 mb against Earth's 1,013 mb; its radius is 0.532 of Earth's.NASA NSSDC, Mars fact sheet
• Liquid water released on Mars will simultaneously freeze and boil.NASA Astrobiology, Liquid water on Mars
• Mars is about half Earth's size; its crust keeps traces of a magnetic field from 4 billion years ago.NASA, Mars facts
• Mars had a thick atmosphere 4 billion years ago; the field made by its core all but disappeared.NASA MAVEN blog, Martian magnetic fields, 2013
• Solar wind and radiation stripped most of Mars's atmosphere over billions of years.NASA, MAVEN reveals most of Mars' atmosphere was lost to space
• Mars has a liquid iron core.NASA JPL, Mars has a liquid iron core, 2023
• Proxima b orbits the nearest star in its habitable zone.ESO, Anglada-Escudé et al. 2016 (eso1629)
• Proxima b has a minimum mass of 1.055 Earth masses.NASA Exoplanet Catalog, Proxima Centauri b
• Proxima is 40,208,000,000,000 km (4.25 light years) away; over 73,000 years at Voyager's speed.NASA Imagine the Universe, nearest star
• An Earth like atmosphere may not survive Proxima b's orbit.NASA Goddard, Garcia-Sage et al. 2017
• Proxima b receives about 250 times more X rays than Earth.Ribas et al. 2016, Astronomy & Astrophysics
• A March 2016 superflare made Proxima about 68 times brighter, just visible to the naked eye at dark sites.Howard et al. 2018, The Astrophysical Journal Letters
• Voyager 1 travels at about 38,000 mph (17.0 km/s).NASA, Voyager 1
• The speed of light in vacuum is a defined constant.NIST, SP 330
• Light could circle Earth about 7.5 times in one second.NASA Glenn, How fast is the speed of light?
• Kinetic energy grows without limit as speed nears light speed.OpenStax College Physics 2e, Relativistic energy
• Moving clocks run slow by the time dilation factor gamma, which grows as speed nears light speed (the formula behind the factor 10.01 at 99.5%).OpenStax University Physics Volume 3, Time dilation
• At about 99.5% of light speed, a traveler celebrates only five birthdays on the voyage while about 50 years pass at home.NASA JPL, Time Travel podcast
• Atomic clocks flown around the world on airliners measured time dilation.Hafele & Keating 1972, Science
• The clocks flown in October 1971 lost 59 billionths of a second eastward and gained 273 westward.HyperPhysics, Airplane clock experiment
• The Sun circles the Milky Way about once every 230 million years.Space.com, Milky Way facts
• One galactic year ago was the Late Triassic, when the first dinosaurs appeared.Live Science, How many times has the Sun traveled around the Milky Way
• The Milky Way and nearby galaxies move at around 600 km/s toward a point beyond the Milky Way's plane, the Great Attractor; we'll never actually get there.BBC Sky at Night, The Great Attractor
• The Great Attractor region hides behind the Milky Way's dust.ESA/Hubble, Picture of the Week potw1302a
• The Shapley supercluster contributes to the Local Group's motion.Kocevski & Ebeling 2006
• Our galaxy belongs to the Laniakea supercluster.Tully et al. 2014, Nature (Laniakea)
• Everything ever observed adds up to less than 5% of the universe.NASA, What is dark energy?
• Dark matter makes up about 27% of the universe.NASA, Dark matter
• Dark matter does not emit, absorb or reflect light.CERN, Dark matter
• The expansion of the universe is accelerating.Nobel Prize in Physics 2011
• The farthest galaxies recede faster than light because space between us is expanding.Davis & Lineweaver 2004
• In about 100 billion years, the nearby galaxies will have merged with the Milky Way and all other galaxies will have disappeared from view.Krauss & Scherrer, Scientific American, 2008
• A deorbit burn starts a spacecraft's return.NASA Commercial Crew blog, 2024
• Orion's heat shield faces temperatures nearing 5,000 °F and burns away to carry heat off.NASA, Orion heat shield
• Plasma around a reentering craft blocks radio signals.ESA, Mitigation of RF blackout
• H. Julian Allen showed blunt bodies survive reentry heating better than sharp ones.NASA Ames History, H. Julian Allen
• The first powered, controlled airplane flight was on December 17, 1903.Smithsonian National Air and Space Museum, 1903 Wright Flyer
• Apollo 11 landed on the Moon on July 20, 1969.NASA, Apollo 11

built from the Season 1 Shorts below

How Long Would It Take to Reach the Nearest Earth Like Planet?

Oct 6 · 1:06 · Space

• At Voyager's speed, reaching Proxima would take over 73,000 years.NASA Imagine the Universe
• Proxima b is 4.2 light years away, at least Earth's mass.NASA Exoplanet Catalog
• Proxima b orbits where liquid water could exist on its surface.ESO, 2016 (Anglada-Escudé et al.)
• Proxima is too faint to see with the naked eye.Space.com
• Proxima b gets hundreds of times Earth's X ray dose.Eos (AGU)
• Proxima b could lose an Earth like atmosphere.NASA Goddard, 2017
• Voyager 1 travels about 17 km per second.NASA, Voyager 1
• The average human generation lasts about 27 years.Wang et al. 2023, Science Advances
• A 2019 flare made Proxima Centauri more than 14,000 times brighter in ultraviolet.MacGregor et al. 2021, via AAS Nova
• Over the past 250,000 years, the average age at which humans had children is 26.9 years (Wang et al. 2023).Indiana University, 2023

Why Can't We Live on Mars?

Oct 5 · 1:09 · Space

• Liquid water on the surface of Mars boils and freezes at once.NASA Astrobiology
• Mars's air pressure is less than 1% of Earth's.NASA Mars Fact Sheet
• Early Mars seems to have had thick air and liquid water.LASP, University of Colorado (MAVEN)
• Martian craters show signs of old lakes and connecting river channels.NASA, MAVEN
• The solar wind is a constant stream of particles from the Sun.NASA Science
• Earth's magnetic field shields its air from the solar wind.NASA Science, Earth's Magnetosphere
• Mars's core made magnetic field all but disappeared.NASA MAVEN blog, 2013
• Mars is smaller than Earth, so it cooled much faster.NASA Goddard, Sun to Earth Day
• At low pressure, like on the surface of Mars, water can boil and freeze at the same time.Exploratorium, Science Snacks: Boyleing Water
• On Mars, water can boil at temperatures as low as 0 °C, and water that emerges immediately starts to boil.Open University / Nature Geoscience (Massé et al. 2016), via ScienceDaily
• Mars's core is still at least partly liquid.NASA JPL (InSight), 2023

What Are Dark Matter and Dark Energy?

Oct 4 · 1:05 · Space

• Everything ever observed adds up to less than 5% of the universe.NASA Science, Dark Energy
• Dark matter makes up about 27% of the universe.NASA Science, Dark Matter
• Vera Rubin found galaxies spin too fast for their visible mass.Smithsonian American Women's History Museum
• If dark matter is particles, many pass through you every second.Freese & Savage 2012, Physics Letters B
• The expansion of the universe is speeding up.Nobel Prize in Physics 2011
• The most distant galaxies recede faster than light as space expands.Davis & Lineweaver 2004, PASA
• In about 100 billion years, other galaxies will vanish from view.Krauss & Scherrer 2007
• Normal matter is 5% of the universe, dark matter about 27%, dark energy about 68%; galaxies spin too fast for their visible matter to hold them together; dark matter does not absorb, reflect or emit light.CERN, Dark matter
• In 1998 astronomers found the expansion is speeding up; it began speeding up about five to six billion years ago.NASA Science, Hubble Finds Evidence for Dark Energy in the Young Universe
• The Local Group will collapse into one large galaxy over about 100 billion years, and all other galaxies will disappear beyond the event horizon.Krauss & Scherrer, Scientific American 2008

How Will the Sun Die?

Oct 3 · 1:05 · Space

• The Sun has about 5 billion years of core hydrogen left.NASA, Sun facts
• The Sun fuses about 600 million tons of hydrogen every second.EUROfusion
• When core hydrogen runs out, the core heats and the star swells.Penn State, ASTRO 801
• As a red giant, the Sun will grow over 200 times wider.Space.com, red giant stars
• The red giant Sun will swallow Mercury and Venus, maybe Earth.Schröder & Smith 2008
• A newer study suggests Earth may survive the Sun's death.Space.com, Earth may survive the Sun's death
• A brightening Sun boils off Earth's oceans in about a billion years.The Conversation (Jillian Scudder)
• The Sun will shed a glowing cloud, leaving an Earth sized white dwarf.NASA Science, Stars
• The red giant Sun reaches a maximum radius of about 1.2 AU; Earth's orbit widens to at most 150% of today's; Earth's engulfment remains uncertain; the oceans are lost 1 to 1.5 billion years from now; the white dwarf keeps about 54% of the Sun's present mass.Wikipedia, Future of Earth, 2026
• A white dwarf is held up by electron degeneracy pressure, can't be crushed below about 1.44 solar masses, and cools over many trillions of years.Wikipedia, White dwarf, 2026
• A planetary nebula is roughly a light year across, lasts a few tens of thousands of years, and is named for its planet like look in early telescopes.Wikipedia, Planetary nebula, 2026

What Is the Great ATTRACTOR?

Oct 2 · 1:11 · Space

• Our galaxy moves about 565 km/s, over a million mph.Planck Collaboration 2018
• In the 1980s, astronomers found nearby galaxies streaming one way.Lynden-Bell et al. 1988, The Astrophysical Journal
• Our galaxy's stars and dust hide about a quarter of the sky.Kraan-Korteweg & Lahav 2000
• A giant galaxy cluster, Norma, sits hidden behind the Milky Way.Kraan-Korteweg et al. 1996, Nature
• X rays reveal the Norma Cluster's hot gas through the dust.Böhringer et al. 1996
• A radio survey found 883 galaxies behind the Milky Way's disk.Staveley-Smith et al. 2016
• The distant Shapley Supercluster also pulls on our galaxy's neighborhood.Kocevski & Ebeling 2006
• Cosmic expansion outpaces the pull, so we never arrive.Tully et al. 2014, Nature
• The Great Attractor is 150 to 250 million light years away; we move toward it at about 600 km/s; we'll never get there because Laniakea isn't gravitationally bound.BBC Sky at Night Magazine
• The Norma Cluster, at the heart of the Great Attractor, lies about 220 million light years away, behind the dust of the Milky Way's plane.ESA/Hubble, Picture of the Week potw1302a
• The Shapley Supercluster is about 650 million light years away, and the Great Attractor and our region are moving toward it.Wikipedia, Shapley Supercluster
• The Seven Samurai studied about 400 elliptical galaxies, and Alan Dressler named the Great Attractor.Wikipedia, Great Attractor
• Laniakea holds about 100,000 galaxies, its name is Hawaiian for "immense heaven", the Great Attractor is its focal point, and it isn't gravitationally bound.Wikipedia, Laniakea Supercluster
• There is a slight preference for our home basin, Laniakea, being part of a much larger Shapley basin of attraction.Valade et al. 2024, Nature Astronomy
• In 2026 astronomers still disagree about how much of our motion the Great Attractor causes.Stiskalek et al. 2026, The Open Journal of Astrophysics
• In 2026 astronomers still disagree about how much of our motion the Great Attractor causes (the other side).Dressler & Monson 2026 (preprint)

Why Can't Anything Travel Faster Than Light?

Oct 1 · 1:24 · Physics

• Light travels 299,792,458 m every second in empty space.NIST, The International System of Units (SP 330)
• Light could circle Earth about 7.5 times in one second.NASA Glenn Research Center
• Reaching light speed would take infinite energy for anything with mass.OpenStax College Physics 2e (Rice University)
• Only massless things, like light, travel at light speed.University of Illinois Physics Van
• At 99.5% light speed, a year aboard is about ten at home.NASA JPL, Time Travel podcast
• A twin who travels near light speed comes home younger.Einstein Online, Max Planck Institute for Gravitational Physics
• Atomic clocks flown around the world came back out of sync.Hafele & Keating 1972, Science
• Light travels about 186,000 miles (300,000 km) per second.NASA Science, What is a light year?
• Kinetic energy is (γ · 1)mc², the formula behind the cost of each extra nine.HyperPhysics, Relativistic Energy (Georgia State University)
• Gamma rays arrived 1.7 seconds after the gravitational waves from GW170817.LIGO Scientific Collaboration, GW170817 and GRB 170817A science summary
• From a delay of 1.74 ± 0.05 s, the speed of gravity differs from the speed of light by between minus 3 × 10⁻¹⁵ and +7 × 10⁻¹⁶ of light speed.LIGO, Virgo, Fermi and INTEGRAL 2017, ApJL 848 L13
• The 2017 neutron star collision was about 130 million light years away.NASA Scientific Visualization Studio #12740
• Predicted and measured clock shifts in the 1971 flights, with their gravity and speed parts.HyperPhysics, Hafele and Keating Experiment
• The flown clocks agreed with special and general relativity within the margin of error.NIST Taking Measure, Putting Einstein to the Test With the World's Most Accurate Clocks
• Traveling near light speed lets you age less than people at home, a trip into the future.Scientific American, Why Einstein's Theories of Relativity Make Time Travel Possible

How Heavy Is a Neutron Star?

Sep 30 · 1:24 · Space

• A teaspoon of neutron star matter would weigh a billion tons.NASA Goddard (NICER mission)
• A typical neutron star packs 1.4 Suns into a city sized ball.University of Maryland (M. Coleman Miller)
• All humans together weigh about 390 million tonnes.Greenspoon et al. 2023, PNAS
• Surface gravity is roughly 100 billion times Earth's.Ohio State University (B. Ryden, Astronomy 162)
• The fastest known pulsar spins 716 times a second.Hessels et al. 2006, Science
• Pulsar beams sweep past Earth like a lighthouse.NRAO
• The 2017 neutron star crash made gold and platinum.LIGO Lab, Caltech
• That one crash made at least 10 Earths' worth of gold.The Conversation (Duncan Brown and Edo Berger)
• A teaspoon of neutron star would have a mass of about a trillion kilograms.ESA/Hubble, Neutron star glossary
• A neutron star forms from a star of about eight or more times the Sun's mass that explodes as a supernova.NASA Science, Star types
• Measured neutron stars are about 24.8 to 27.4 km (15.4 to 17 miles) across; J0030 is about 1.4 Suns and about 26 km (16 miles) across.NASA, NICER probes the squeezability of neutron stars, 2021
• The nucleus holds more than 99.9% of an atom's mass but is only 1/100,000 the diameter of the electron cloud.Chandra X ray Center, Field Guide: Neutron Stars
• The core collapse crushes protons and electrons together into neutrons; a pulsar is like a lighthouse.NASA Imagine the Universe, Neutron Stars
• Surface gravity is about 200 billion times Earth's (upper end of the range).University of Illinois Physics Van
• Neutron stars are about 95 percent neutrons.Symmetry magazine, Five extreme facts about neutron stars, 2017
• The 2017 crash may have made around 200 Earth masses of gold.UC Berkeley News, 2017
• Gold's origin is not solved; magnetar giant flares may contribute some heavy elements.NASA Science, Where Does Gold Come From? NASA Data Has Clues, 2025
• Collapsars may be a major source of the heaviest elements.Siegel, Barnes & Metzger 2019, Nature

How Hot Is Earth's Core?

Sep 29 · 1:23 · Earth science

• Earth's inner core reaches about 5,400 °C (9,800 °F).NASA, Earth facts
• The Sun's surface is about 5,500 °C (10,000 °F).NASA, Sun facts
• The deepest hole ever dug reached about 7.5 miles.Scientific American
• Earth's center is about 4,000 miles down.NASA Earth Fact Sheet
• Mantle rock flows about as fast as fingernails grow.USGS
• Pluto is 2,377 km wide, close to the inner core's width.NASA, Pluto facts
• Churning liquid iron in the outer core makes Earth's magnetic field.USGS
• The solar wind stripped away most of Mars's atmosphere.NASA, MAVEN
• Lab work puts the temperature at the inner core's edge at 6,000 °C, plus or minus 500, at 3.3 million atmospheres; iron squeezed between diamonds and heated with lasers.ESRF, 2013
• Pressure at the center is nearly 3.6 million atmospheres, too great for iron atoms to move into a liquid state; S waves can't pass through fluids.National Geographic Education, Core
• The outer core begins about 2,889 km (1,795 miles) below the surface and is mostly iron and nickel.Wikipedia, Earth's outer core
• Most of the solar wind is deflected by Earth's magnetosphere; particles that get in spiral toward the poles and help make auroras.NASA, What Is the Solar Wind?
• Mars lost its global magnetic field about 3.7 billion years ago.NASA, MAVEN video release
• The solar wind strips about 100 grams (roughly a quarter pound) of Mars's atmosphere every second.NASA, MAVEN solar wind release, 2015
• S waves can't pass through the liquid outer core, which shows the outer core is liquid.Wikipedia, Shadow zone
• Inge Lehmann discovered the solid inner core in 1936.Wikipedia, Inge Lehmann
• How much a magnetic field protects an atmosphere is debated; Earth, Mars and Venus lose gas at similar rates, though Mars and Venus have no field of their own.Gunell et al., 2018

How Do Astronauts Come Back to Earth?

Sep 28 · 1:22 · Physics

• A capsule starts its return at about 17,500 mph.NASA Commercial Crew blog, 2024
• A short engine burn against the direction of travel starts reentry.FAA, Returning from Space
• Reentry heat comes mainly from compressed air, not friction.Wikipedia, Atmospheric entry
• Air squeezed ahead of the capsule heats to several thousand degrees.ESA
• A blunt shape pushes the shock wave out ahead of the capsule.NASA History, SP 4209
• Heat shields burn away on purpose, carrying heat off with them.NASA, Orion heat shield
• Hot plasma around a returning capsule blocks radio signals.ESA
• Crew Dragon's drogue chutes open at about 350 mph.NASA Commercial Crew blog, 2024
• Crew Dragon enters the atmosphere at about 17,500 mph.Wccftech, SpaceX Crew Dragon reentry footage
• Over 80% of the Space Shuttle's heating during reentry was caused by compression, not friction.Wikipedia, Space Shuttle thermal protection system
• A fast vehicle heats the air in front of it and turns it into plasma, which blocks radio.Scientific American, Piercing the Plasma
• H. Julian Allen developed the blunt body concept at the NACA Ames Aeronautical Laboratory.Vincenti, Boyd and Bugos, H. Julian Allen: An Appreciation, 2007

How Do Rockets Get to Space?

Sep 28 · 1:30 · Physics

• Saturn V's first stage made about 7.5 million pounds of thrust.BBC Science Focus
• Saturn V's first stage burned over 13 tons of propellant a second.BBC Science Focus
• Low Earth orbit takes a speed of about 17,500 mph.Space.com
• Orbiting spacecraft are in free fall around Earth.NASA STEMonstrations: Orbits