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OpenStem
@openstem · Joined Jul 2026
7420 public items8 groups
Collection3 items
01Astronomy · L5 · Magnetar Physics
02Astronomy · L5 · Magnetars: Extreme Fields, Giant Flares, and the Fast Radio Burst Connection
03Astronomy · L5 · Magnetar Physics
Astronomy · L5 · Magnetar Physics
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Astronomy · L5 · Magnetar PhysicsCollection4 items
01Astronomy · L5 · Multi-Messenger Astronomy
02Astronomy · L5 · Multi-Messenger Astronomy: Gravitational Waves, Neutrinos, and Light from One Event
03Astronomy · L5 · The GW170817 Multi-Messenger Detection Timeline
+1 moreAstronomy · L5 · Multi-Messenger Astronomy
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Astronomy · L5 · Multi-Messenger AstronomyCollection4 items
01Astronomy · L5 · Relativistic Jets: Doppler Beaming & Superluminal Motion
02Astronomy · L5 · Relativistic Jets: Doppler Beaming and Apparent Superluminal Motion
03Astronomy · L5 · Approaching Jet or Receding Counter-Jet?
+1 moreAstronomy · L5 · Relativistic Jets: Doppler Beaming & Superluminal Motion
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Astronomy · L5 · Relativistic Jets: Doppler Beaming & Superluminal MotionCollection4 items
01Astronomy · L5 · Neutron-Capture Nucleosynthesis: the s-process and r-process
02Astronomy · L5 · Neutron-Capture Nucleosynthesis: the s-process and r-process
03Astronomy · L5 · s-process or r-process?
+1 moreAstronomy · L5 · Neutron-Capture Nucleosynthesis: the s-process and r-process
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Astronomy · L5 · Neutron-Capture Nucleosynthesis: the s-process and r-processCollection3 items
01Astronomy · L5 · Ultra-High-Energy Cosmic Rays & the GZK Cutoff
02Astronomy · L5 · Ultra-High-Energy Cosmic Rays & the GZK Cutoff
03Astronomy · L5 · Ultra-High-Energy Cosmic Rays & the GZK Cutoff
Astronomy · L5 · Ultra-High-Energy Cosmic Rays & the GZK Cutoff
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Astronomy · L5 · Ultra-High-Energy Cosmic Rays & the GZK CutoffCollection3 items
01Astronomy · L5 · Strong-Lensing Time-Delay Cosmography & the Hubble Tension
02Astronomy · L5 · Strong-Lensing Time-Delay Cosmography & the Hubble Tension
03Astronomy · L5 · Strong-Lensing Time-Delay Cosmography & the Hubble Tension
Astronomy · L5 · Strong-Lensing Time-Delay Cosmography & the Hubble Tension
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Astronomy · L5 · Strong-Lensing Time-Delay Cosmography & the Hubble TensionCollection3 items
01Astronomy · L5 · The Kerr Metric: Frame Dragging, the Ergosphere & the Penrose Process
02Astronomy · L5 · The Kerr Metric: Frame Dragging, the Ergosphere & the Penrose Process
03Astronomy · L5 · Crossing Toward a Rotating Black Hole
Astronomy · L5 · The Kerr Metric: Frame Dragging, the Ergosphere & the Penrose Process
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Astronomy · L5 · The Kerr Metric: Frame Dragging, the Ergosphere & the Penrose ProcessFlashcards7 cards
What is a solar eclipse?1 / 7
When the Moon passes between the Sun and Earth, blocking some or all of the Sun's light.
Astronomy · L1 · Solar and Lunar Eclipses
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Astronomy · L1 · Solar and Lunar EclipsesFlashcards5 cards
How many planets are in our solar system?1 / 5
There are eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto is now called a dwarf planet.
Astronomy · L1 · Planets in Our Solar System
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Astronomy · L1 · Planets in Our Solar SystemFlashcards5 cards
Why do we have day and night?1 / 5
Earth spins around. The side facing the Sun gets daylight. The side facing away gets night.
Astronomy · L1 · Day and Night
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Astronomy · L1 · Day and NightFlashcards8 cards
What is a 'moon phase'?1 / 8
A moon phase is the shape of the sunlit part of the Moon that we can see from Earth.
Astronomy · L1 · The Changing Moon
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Astronomy · L1 · The Changing MoonFlashcards8 cards
What is the Sun?1 / 8
The Sun is a star — a giant ball of very hot, glowing gas.
Astronomy · L1 · The Sun, Our Star
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Astronomy · L1 · The Sun, Our StarFlashcards8 cards
What is a constellation?1 / 8
A group of stars that seems to form a picture or shape in the sky.
Astronomy · L1 · Stars and Constellations
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Astronomy · L1 · Stars and ConstellationsFlashcards8 cards
What is an asteroid?1 / 8
A rocky object that orbits the Sun, smaller than a planet.
Astronomy · L1 · Asteroids, Comets, and Meteors
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Astronomy · L1 · Asteroids, Comets, and MeteorsFlashcards8 cards
What is gravity?1 / 8
A pulling force that pulls every object toward every other object.
Astronomy · L1 · Gravity
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Astronomy · L1 · GravityFlashcards8 cards
Why do we need rockets to reach space?1 / 8
Earth's gravity is very strong, so escaping it takes tremendous speed — only powerful rockets can do that.
Astronomy · L1 · Rockets
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Astronomy · L1 · RocketsFlashcards8 cards
What is an astronaut?1 / 8
A person specially trained to travel and work in space.
Astronomy · L1 · Astronauts
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Astronomy · L1 · AstronautsFlashcards8 cards
What does a telescope do?1 / 8
It collects much more light than our eyes can, making faraway objects look bigger and brighter.
Astronomy · L1 · Telescopes
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Astronomy · L1 · TelescopesFlashcards8 cards
Why is Earth sometimes called the 'Goldilocks planet'?1 / 8
Because it is not too hot and not too cold — just the right distance from the Sun for liquid water to exist.
Astronomy · L1 · Why Earth Is Special
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Astronomy · L1 · Why Earth Is SpecialFlashcards8 cards
How many seasons are there, and what are their names?1 / 8
Four: spring, summer, fall (autumn), and winter.
Astronomy · L1 · The Four Seasons
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Astronomy · L1 · The Four SeasonsFlashcards8 cards
What is the International Space Station (ISS)?1 / 8
A giant spacecraft that orbits Earth, where astronauts live and work for months at a time.
Astronomy · L1 · The Space Station
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Astronomy · L1 · The Space StationFlashcards8 cards
What was the name of the program that landed humans on the Moon?1 / 8
The Apollo program, run by NASA.
Astronomy · L1 · Humans on the Moon
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Astronomy · L1 · Humans on the MoonFlashcards8 cards
What is a meteor shower?1 / 8
An event where many meteors, or 'shooting stars', appear in a short time, seeming to come from one part of the sky.
Astronomy · L1 · Meteor Showers
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Astronomy · L1 · Meteor ShowersFlashcards8 cards
What is an aurora?1 / 8
A colorful, moving glow of light in the night sky, usually seen close to the North or South Pole.
Astronomy · L1 · Northern Lights (Auroras)
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Astronomy · L1 · Northern Lights (Auroras)Flashcards8 cards
What is a satellite?1 / 8
Any object that orbits, or travels around, a larger object in space.
Astronomy · L1 · Satellites: Natural & Artificial
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Astronomy · L1 · Satellites: Natural & ArtificialFlashcards8 cards
Why is Mars nicknamed the 'Red Planet'?1 / 8
Iron-rich dust covering its surface has rusted, giving Mars a reddish color.
Astronomy · L1 · Mars Exploration
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Astronomy · L1 · Mars ExplorationFlashcards8 cards
Do you need a telescope to enjoy stargazing?1 / 8
No — you can spot lots of stars, planets, and patterns using just your eyes.
Astronomy · L1 · Finding Stars & Planets in the Sky
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Astronomy · L1 · Finding Stars & Planets in the SkyFlashcards8 cards
What does 'one year' actually measure?1 / 8
The time it takes Earth to travel all the way around the Sun once.
Astronomy · L1 · Why a Year Has 365 Days
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Astronomy · L1 · Why a Year Has 365 DaysFlashcards8 cards
Why is Venus sometimes called Earth's 'twin'?1 / 8
It is very close to Earth in size and made of similar rocky material.
Astronomy · L1 · Venus, Earth's Unfriendly Twin
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Astronomy · L1 · Venus, Earth's Unfriendly TwinFlashcards8 cards
Who first suggested that the Sun, not Earth, is the center of the solar system?1 / 8
Nicolaus Copernicus.
Astronomy · L1 · Astronomers Who Changed How We See the Sky
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Astronomy · L1 · Astronomers Who Changed How We See the Sky