Space Vocabulary Explained: Orbit, Gravity, Nebula, Asteroid, and More
This beginner-friendly space vocabulary guide explains essential astronomy terms such as orbit, gravity, nebula, asteroid, comet, meteor, galaxy, light-year, telescope, spectrum, redshift, black hole, and exoplanet. Instead of presenting space words as a simple glossary, the article organizes them into six practical categories: object, place, motion, force, measurement, and observation. Readers learn how to tell the difference between commonly confused terms, including asteroid vs. comet, meteoroid vs. meteor vs. meteorite, galaxy vs. universe, rotation vs. revolution, and light-year vs. time. The guide also includes a quick sorting tool, a beginner vocabulary compass, common mistakes to avoid, and clear boundaries about what the article does and does not claim. Written for students, parents, and general readers, it uses stable explanations and references from NASA, ESA, ESA/Hubble, and the International Astronomical Union.
Quick Utility Box: Sort Any Space Word in Five Questions
When you meet a new space word, do not start by memorizing it. First, sort it.
- Is it an object? Examples: planet, star, moon, asteroid, comet.
- Is it a place or region? Examples: galaxy, Solar System, nebula, asteroid belt.
- Is it describing motion? Examples: orbit, rotation, revolution.
- Is it describing a force or attraction? Examples: gravity, attraction.
- Is it a measurement or observation word? Examples: light-year, astronomical unit, spectrum, telescope.
This sorting method prevents many beginner mistakes. A light-year is not an object. A nebula is not a galaxy. A meteor is not a star. An orbit is not a place by itself; it is a path.
Core Terms at a Glance
| Term | Beginner meaning |
|---|---|
| Space | The broad environment beyond Earth where cosmic objects, particles, fields, and radiation exist |
| Universe | The total cosmic system that includes space, time, matter, energy, and the physical laws scientists use to describe them |
| Galaxy | A huge gravity-bound system of stars, gas, dust, dark matter, and other cosmic material |
| Solar System | The Sun and the objects gravitationally bound to it |
| Star | A hot, massive object that shines mainly because of internal energy production, especially nuclear fusion during the main part of its active life |
| Planet | A large natural world usually described as orbiting a star or stellar remnant and not shining by its own nuclear fusion |
| Moon | A natural satellite orbiting a planet, dwarf planet, or small body |
| Orbit | A curved path shaped by gravity and motion |
| Gravity | The attraction between masses |
| Nebula | A cloud of gas and dust in space |
| Asteroid | A mostly rocky or metallic small body orbiting the Sun |
| Comet | An icy small body that can release gas and dust near the Sun |
| Meteor | The light event caused when a small object enters an atmosphere |
| Light-year | The distance light travels in one year |
| Astronomical unit | A standard distance unit based on the Earth-Sun distance |
| Telescope | A tool for collecting light or other signals from distant objects |
Use this table as a quick map, not as a replacement for the full explanations below.
Who This Article Is / Is Not For
This article is for beginners, students, parents, and general readers who want space vocabulary explained in plain English.
It is not for mission planning, telescope purchasing decisions, asteroid impact risk assessment, meteorite identification, legal ownership questions, aviation, navigation, or advanced orbital mechanics. When a term has a technical definition, this guide explains the safe beginner meaning and points to authoritative sources for deeper reading.
How This Article Was Reviewed
This guide was checked against public educational material from NASA, ESA, ESA/Hubble, and the International Astronomical Union. It focuses on stable vocabulary rather than changing live data such as current asteroid counts, spacecraft positions, or newly announced discoveries.
Useful source references include:
- NASA Science: Universe Glossary
- NASA Basics of Spaceflight: Units of Measure
- ESA: Types of Orbits
- ESA/Hubble Word Bank: Nebula
- NASA: Asteroids, Comets, and Meteors
- IAU: Meteors and Meteorites
- NASA Space Place: What Is a Light-Year?
- NASA: What Is an Exoplanet?
- NASA: Black Hole Anatomy
- NASA: The Electromagnetic Spectrum
- NASA/Hubble: Cosmological Redshift
- IAU FAQ: Pluto and Planet Definition
1. Space
“Space” usually means the vast region beyond Earth’s atmosphere. In everyday use, it refers to the environment where planets, moons, stars, galaxies, gas, dust, radiation, and spacecraft exist.
Space is not perfect emptiness. Even areas that look empty may contain particles, plasma, magnetic fields, radiation, dust, and gravitational influence. The vacuum of space is very different from ordinary air, but it is not absolute nothingness.
Space is the large physical environment beyond Earth where astronomical objects, fields, particles, and radiation exist.
One boundary note matters: space does not begin at a simple wall. Earth’s atmosphere gradually becomes thinner with altitude. Different organizations may use different practical boundaries for aviation, science, policy, or record-keeping. For this vocabulary guide, “space” is treated as a broad physical environment rather than a legal boundary.
2. Universe
The universe is the broadest word in this guide. It refers to space, time, matter, energy, and the physical laws scientists use to describe them.
The universe includes galaxies, stars, planets, nebulae, black holes, radiation, dark matter, and everything else science can observe or infer. A galaxy is not the universe. The Solar System is not the universe.
The universe is the total cosmic system that includes space, time, matter, energy, and the physical laws scientists use to describe them.
You may also see the phrase observable universe. This means the part of the universe from which light has had time to reach us. It does not necessarily mean the entire universe. It means the portion we can observe from our location and cosmic history.
That distinction matters. “Universe” is the broad concept. “Observable universe” is the part available to observation from where we are.
3. Galaxy
A galaxy is a huge system of stars, gas, dust, dark matter, and other material held together by gravity. Our home galaxy is the Milky Way.
A galaxy can contain billions or even hundreds of billions of stars. It may also contain nebulae, star clusters, planets, black holes, and large regions of gas and dust.
A galaxy is a gravity-bound system containing stars, gas, dust, dark matter, and other cosmic material.
A helpful scale check:
| Term | What it means |
|---|---|
| Solar System | The Sun and the objects bound to it |
| Milky Way | The galaxy that contains the Sun |
| Universe | The broadest cosmic system described in astronomy |
The Milky Way is enormous from a human point of view, but it is still only one galaxy. The universe contains galaxies; a galaxy does not contain the whole universe.
4. Solar System
The Solar System is the Sun and the objects gravitationally bound to it. This includes eight major planets, dwarf planets, moons, asteroids, comets, meteoroids, dust, and distant icy bodies.
The Solar System is the Sun-centered system of planets and smaller bodies held by the Sun’s gravity.
The word solar refers to the Sun. That is why “the Solar System” refers specifically to our Sun’s system. When scientists talk about planets around other stars, they often use terms such as planetary system or exoplanet system.
In casual speech, people sometimes say “another solar system.” In careful writing, “another planetary system” is usually better.
5. Star
A star is a hot, massive object that produces light and energy from processes inside it, especially nuclear fusion during the main part of its active life. The Sun is the nearest active star to Earth.
A star is a hot, massive object that shines mainly because of internal energy production, especially nuclear fusion during the main part of its active life.
Stars are not simply bright dots. They have mass, temperature, magnetic activity, lifetimes, and stages of change. Some stars are young and blue-white. Some become red giants. Some end as white dwarfs, neutron stars, or black holes, depending on their mass and history.
A common misunderstanding is that the brightest-looking star in the sky must be the closest or largest. How bright a star looks from Earth depends on both its true brightness and its distance from us.
6. Planet
For beginner vocabulary, a planet is usually described as a large natural world that orbits a star or stellar remnant and does not shine by its own nuclear fusion.
A planet is a large natural world usually described as orbiting a star or stellar remnant and not shining by its own nuclear fusion.
In the Solar System, the eight recognized major planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto is classified as a dwarf planet.
Planet classification can be more technical than the everyday word suggests. The International Astronomical Union’s Solar System planet definition includes criteria such as orbiting the Sun, being rounded by self-gravity, and clearing the neighborhood around its orbit.
For general readers, the safe takeaway is this: “planet” is not just another word for “round object in space.” The category depends on orbit, physical properties, and scientific context.
7. Moon
A moon is a natural satellite. It orbits a planet, dwarf planet, or small body. Earth has one large natural moon, usually called the Moon. Other planets can have many moons.
A moon is a natural satellite that orbits a larger body other than a star.
The word satellite can mean either natural or artificial. The Moon is a natural satellite. A weather satellite orbiting Earth is an artificial satellite.
Moons do not have to be tiny. Some moons are large and complex worlds. Jupiter’s moon Ganymede, for example, is larger than the planet Mercury. Its classification as a moon comes from what it orbits, not only from its size.
8. Orbit
An orbit is the curved path one object follows around another object because of gravity and motion. ESA describes orbit as a path around another body due to gravity.
An orbit is a curved path around another body, shaped by gravity and forward motion.
An orbiting object is not simply floating. It is falling toward the body it orbits while also moving forward fast enough that it keeps missing the surface. This is why spacecraft and astronauts in low Earth orbit can experience weightlessness. They are falling together around Earth.
Orbit does not mean gravity is absent. Gravity is the reason the orbit exists.
Examples:
- The Moon orbits Earth.
- Earth orbits the Sun.
- Many artificial satellites orbit Earth.
- Some spacecraft orbit planets, moons, asteroids, or the Sun.
- Comets can follow long paths around the Sun.
The beginner mistake to avoid is saying “there is no gravity in orbit.” There is gravity in orbit. Weightlessness happens because of continuous free fall, not because gravity has disappeared.
9. Gravity
Gravity is the natural attraction between objects with mass. It pulls planets toward stars, moons toward planets, and matter together during the formation of stars, planets, and galaxies.
Gravity is the attraction between masses that shapes orbits, worlds, stars, and large cosmic structures.
Gravity helps:
- keep Earth in orbit around the Sun;
- keep the Moon in orbit around Earth;
- gather gas and dust during star formation;
- shape galaxies and galaxy clusters;
- influence the paths of spacecraft, comets, and asteroids.
Gravity is not the same as magnetism. Magnets involve electromagnetic forces. Gravity involves mass and, in modern physics, the structure of spacetime. For a beginner, the key point is simpler: gravity is the main reason large objects in space move together in predictable paths.
10. Rotation and Revolution
Rotation and revolution are easy to mix up.
Rotation means an object spins around its own axis. Revolution means an object travels around another object.
Earth rotates once in about a day, producing the cycle of day and night. Earth revolves around the Sun in about a year.
The simplest memory trick is:
- Rotation = spin
- Revolution = orbit around something
So Earth does not “rotate around the Sun.” Earth rotates on its axis and revolves around the Sun.
11. Nebula
A nebula is a cloud of gas and dust in space. Some nebulae are regions where stars form. Others are connected to dying stars or the remains of stellar explosions.
A nebula is a cloud of gas and dust in space, often connected to star birth, star death, or interstellar material.
Common types include:
| Type | Beginner meaning |
|---|---|
| Emission nebula | Gas glows after being energized by nearby stars |
| Reflection nebula | Dust reflects light from nearby stars |
| Dark nebula | Dust blocks light from objects behind it |
| Planetary nebula | A gas shell from a dying Sun-like star |
| Supernova remnant | Expanding debris from a stellar explosion |
The name “planetary nebula” is historical. It does not mean the nebula contains planets. Early telescope observers thought some of these objects looked planet-like, but modern astronomy understands them as material shed by dying stars.
A nebula is also not the same thing as a galaxy. A nebula is a cloud or region of material. A galaxy is a much larger gravity-bound system.
12. Asteroid
An asteroid is a small rocky or metallic body orbiting the Sun. Many asteroids are found in the asteroid belt between Mars and Jupiter, though asteroids also exist in other orbital regions.
An asteroid is a mostly rocky or metallic small body orbiting the Sun.
Asteroids are important because many are leftover material from the early Solar System. They help scientists study the ingredients that existed when planets were forming.
A safe beginner distinction:
- Asteroids are generally rocky or metallic.
- Comets are generally ice-rich and can become active near the Sun.
- Meteoroids are smaller natural objects or fragments traveling through space.
The boundary is not always perfect. Some objects blur the line between asteroid and comet, especially if they have unusual compositions or activity. For beginner reading, however, “rocky asteroid” and “icy comet” is a useful first distinction.
A common mistake is describing all asteroids as immediate threats. Most known asteroids are not on impact paths with Earth. Risk assessment requires professional tracking and orbital analysis.
13. Comet
A comet is an icy small body that orbits the Sun. When it comes close enough to the Sun, its ices can warm and release gas and dust, forming a glowing coma and sometimes a tail.
A comet is an icy small body that can release gas and dust when warmed by the Sun.
A comet’s tail does not simply trail behind it like smoke from a moving car. Comet tails are shaped by sunlight and the solar wind, so they often point generally away from the Sun.
Comets are not “burning” like wood in a fire. Their visible activity comes from warming, gas release, dust, sunlight, and charged particles interacting around the comet’s nucleus.
14. Meteoroid, Meteor, and Meteorite
These three words describe related stages of a small object’s journey.
| Term | Where it is | What it means |
|---|---|---|
| Meteoroid | In space | A small natural solid object moving through space |
| Meteor | In an atmosphere | The light event caused by entry into an atmosphere |
| Meteorite | On the ground | A surviving piece that reaches a surface |
A “shooting star” is not a star. It is a meteor.
The beginner version is simple: space object, sky streak, ground fragment.
Safety note: if you think you have found a meteorite, treat this article as vocabulary help only. Identification can be difficult, local rules vary, and many suspected meteorites are ordinary Earth rocks sometimes called meteor-wrongs.
15. Dwarf Planet
In the Solar System, a dwarf planet is a rounded body that orbits the Sun but has not cleared its orbital neighborhood in the way a major planet has.
A dwarf planet is a rounded Sun-orbiting body that is planet-like but belongs to a separate classification.
Pluto is the most famous dwarf planet. Ceres, located in the asteroid belt, is another example.
The important point is that Pluto did not physically change when its classification changed. The object stayed the same. The category changed because astronomers refined how they classify objects in the Solar System.
For readers, this is a useful reminder: scientific classification is not always a judgment about importance. It is a way of sorting objects more precisely.
16. Exoplanet
An exoplanet is a planet beyond our Solar System. NASA commonly describes exoplanets as worlds beyond our Solar System, and most known exoplanets orbit other stars. They can vary widely in size, temperature, composition, and orbit.
An exoplanet is a planet beyond our Solar System.
Some exoplanets are gas giants. Some are rocky. Some are extremely hot because they orbit close to their stars. Some are cold and distant. Some orbit two stars.
A common mistake is assuming “Earth-sized” means “Earth-like.” A planet can be similar in size to Earth but have a very different atmosphere, temperature, orbit, surface, or star environment.
“Exoplanet” means location category first: beyond our Solar System. It does not automatically mean habitable, comfortable, or similar to Earth.
17. Light-Year
A light-year is a unit of distance. It means the distance light travels in one Earth year.
A light-year is the distance light travels in one year.
The word contains “year,” but it does not measure time by itself. It measures distance using light travel.
Why does this matter? Looking far into space also means looking into the past, because light takes time to reach us. If a star is 100 light-years away, the light reaching our eyes or telescopes left that star about 100 years ago.
The mistake to avoid is saying “that galaxy is many years away” when you mean “many light-years away.” Age and distance are related in some astronomy discussions, but the words are not interchangeable.
18. Astronomical Unit
An astronomical unit, often shortened to AU, is a standard distance unit based on the Earth-Sun distance. It is especially useful for talking about distances inside the Solar System.
An astronomical unit is a standard distance unit based on the Earth-Sun distance.
Use AU for Solar System distances, such as the distance from the Sun to planets or the scale of asteroid and comet orbits. Use light-years for much larger distances between stars and galaxies.
A beginner mistake is using light-years for everything. The Solar System is large, but it is tiny compared with the distances between stars.
19. Black Hole
A black hole is a region of spacetime where gravity is so strong that nothing, not even light, can escape from inside its event horizon.
A black hole is a region of spacetime where gravity is so intense that light cannot escape from within a boundary called the event horizon.
Black holes are not magic vacuum cleaners that automatically suck in everything nearby. Objects can orbit a black hole if they are far enough away and moving in the right way.
The danger comes from being too close, not from the mere existence of a black hole somewhere in space.
A helpful beginner comparison: if a black hole had the same mass as another object and you stayed the same distance away, its gravitational pull at that distance would depend on mass and distance, not on the word “black hole.” The extreme effects happen near the event horizon.
20. Event Horizon
An event horizon is the boundary around a black hole beyond which light and matter cannot escape.
An event horizon is the point-of-no-return boundary around a black hole.
It is not a solid surface like the ground. It is a boundary defined by gravity and spacetime. Once something passes inward across that boundary, it cannot send light or information back out in the ordinary way.
For beginners, the most important correction is this: the event horizon is not the black hole’s “surface” in the everyday sense of a hard shell. It is a boundary of escape.
21. Atmosphere
An atmosphere is the gas envelope around a planet, moon, or other body, held by gravity.
Atmospheres can affect temperature, pressure, surface conditions, spacecraft entry, and what telescopes can detect. Do not assume every atmosphere is Earth-like.
22. Vacuum
A vacuum is a region with far less matter than ordinary air, though not necessarily zero matter.
Space can still contain atoms, dust, plasma, radiation, magnetic fields, and gravitational influence. Sound needs a medium to travel, while light can travel through space without air.
23. Radiation
Radiation is energy traveling as waves or particles. In astronomy, radiation can include visible light, radio waves, infrared light, ultraviolet light, X-rays, gamma rays, and energetic particles.
Radiation is energy that travels through space as waves or particles.
Not all radiation is dangerous. Visible light and radio waves are forms of radiation. Higher-energy forms, including some ultraviolet radiation, X-rays, gamma rays, and energetic particles, can be hazardous in certain conditions.
A common beginner mistake is treating “radiation” as always meaning nuclear danger. In space science, radiation often means the signals that allow astronomers to study distant objects.
24. Spectrum
A spectrum is light separated by wavelength. Astronomers use spectra to learn what objects are made of, how hot they are, how they move, and sometimes what gases are present.
A spectrum is light spread out by wavelength, often used as a scientific fingerprint.
Atoms and molecules absorb or emit light at particular wavelengths. These patterns can reveal chemical elements and physical conditions.
This is one reason telescopes are not only “space cameras.” They are measurement tools. A beginner may think a space image shows exactly what the human eye would see. Sometimes it does. Often, scientific images use filters, wavelengths, and processing choices to reveal information that human eyes alone could not detect.
25. Redshift and Blueshift
Redshift means light is shifted toward longer wavelengths. Blueshift means light is shifted toward shorter wavelengths.
Redshift and blueshift describe changes in light wavelength, often connected to motion or cosmic expansion.
For many nearby objects, redshift can suggest motion away from us, while blueshift can suggest motion toward us. For distant galaxies, redshift is also connected to the expansion of space itself.
The safe beginner takeaway is: redshift and blueshift are not colors in the ordinary paint-box sense. They are changes in measured wavelengths.
This guide keeps the idea simple; professional astronomy may distinguish Doppler redshift, gravitational redshift, and cosmological redshift.
26. Telescope
A telescope is an instrument that collects distant light or other signals so scientists can study objects in space.
Magnification is not the only important feature. Light-gathering power, resolution, wavelength, detector quality, and observing location also matter.
27. Spacecraft, Probe, Orbiter, Lander, and Rover
A spacecraft is the broad word for a machine designed to operate in space. A probe is usually an uncrewed spacecraft sent to study a target. An orbiter goes into orbit around a planet, moon, asteroid, or the Sun. A lander is designed to land on a surface. A rover is a mobile robot that moves across a surface.
Spacecraft is the broad word; probe, orbiter, lander, and rover describe more specific mission roles.
Do not call every spacecraft a rocket. A rocket launches or propels. A spacecraft is the vehicle or machine that operates in space.
A Space Vocabulary Compass for Beginners
Use this compass when a space word feels confusing:
| If the word answers... | It is probably about... | Examples |
|---|---|---|
| What is it? | Object type | star, planet, moon, asteroid |
| Where is it? | Place or region | galaxy, nebula, Solar System |
| What is it doing? | Motion | orbit, rotation, revolution |
| Why does it move? | Force or attraction | gravity |
| How far is it? | Measurement | light-year, astronomical unit |
| How do we know? | Observation | telescope, spectrum, redshift |
This compass gives beginners a quick way to avoid category errors.
For example:
- Light-year belongs under measurement, not ordinary time.
- Orbit belongs under motion, not place.
- Nebula belongs under cloud or region, not galaxy.
- Meteor belongs under event, not star.
- Telescope belongs under observation, not space object.
- Gravity belongs under force or attraction, not “space air.”
Once you know the category, the word becomes easier to understand.
Common Space Vocabulary Mistakes to Avoid
Mistake 1: Thinking space is perfect emptiness. Space is much emptier than air, but it can still contain particles, radiation, magnetic fields, dust, and gravity.
Mistake 2: Saying there is no gravity in space. Gravity exists in space. Orbits happen because of gravity.
Mistake 3: Calling a light-year a unit of time. A light-year is a distance unit based on light travel.
Mistake 4: Calling a meteor a falling star. A meteor is not a star. It is a light event in an atmosphere.
Mistake 5: Treating asteroids and comets as identical. They overlap in some complex cases, but the beginner distinction is rocky or metallic asteroid versus ice-rich comet.
Mistake 6: Assuming every nebula forms stars. Some nebulae are star-forming regions. Others are linked to dying stars or explosion debris.
Mistake 7: Confusing the Solar System with the Milky Way. The Solar System is inside the Milky Way. The Milky Way is a galaxy.
Mistake 8: Thinking comet tails are fire. Comet tails are shaped by gas, dust, sunlight, and the solar wind, not by ordinary burning.
Mistake 9: Assuming space images always show human-eye color. Many scientific images use filters or wavelengths outside ordinary vision to reveal hidden structure.
Mistake 10: Treating scientific classifications as insults. Calling Pluto a dwarf planet does not make Pluto unimportant. It places Pluto in a more precise scientific category.
Why You Can Trust This Article
This guide is built as a vocabulary reference, not as a sensational space story. It uses stable definitions, separates beginner meanings from technical details, and links to recognized science organizations for deeper reading.
It avoids exaggerated claims about asteroid danger, alien life, cosmic disasters, or current discoveries. Some astronomy terms have formal definitions or historical meanings that depend on context, so this guide explains the beginner meaning without pretending that simplified definitions replace professional science.
The article also avoids live numerical claims that can change quickly, such as current asteroid counts, current spacecraft positions, or newly announced exoplanet totals.
What This Article Does Not Claim
This article does not claim that every astronomy term has only one simple meaning in all contexts. It does not replace NASA, ESA, IAU, university, observatory, legal, safety, or professional scientific resources.
It also does not provide professional asteroid risk analysis, meteorite identification, telescope-buying advice, spacecraft operation guidance, legal ownership guidance, or real-time discovery updates. It is a learning guide for general readers.
FAQ
What is the easiest way to learn space vocabulary?
Learn words by category. Ask whether the word describes an object, place, motion, force, measurement, or observation method. This is easier than memorizing terms alphabetically.
What is the difference between orbit and rotation?
An orbit is movement around another body. Rotation is spinning around an object’s own axis. Earth rotates on its axis and orbits the Sun.
Is there gravity in space?
Yes. Gravity exists in space. Orbits happen because of gravity. Astronauts in orbit feel weightless because they and their spacecraft are in continuous free fall.
Is a meteor the same as a meteorite?
No. A meteor is the light event in an atmosphere. A meteorite is a surviving piece that reaches the ground.
Is a nebula the same as a galaxy?
No. A nebula is a cloud of gas and dust. A galaxy is a much larger gravitational system containing stars, gas, dust, dark matter, and many other objects.
Is a light-year time or distance?
A light-year is distance. It is the distance light travels in one year.
Is Pluto still real even though it is called a dwarf planet?
Yes. Pluto did not physically change. Its classification changed. It remains a real and scientifically important world.
Are all stars suns?
In casual language, people sometimes call stars “suns,” but the Sun is the proper name of our star. Other stars may have planets of their own, but they are not our Sun.
Does exoplanet mean Earth-like?
Some exoplanets may share traits with Earth, such as size or rocky composition, but “exoplanet” only means a planet beyond our Solar System. It does not automatically mean habitable, comfortable, or Earth-like.
Why do space terms sometimes change?
Science improves through better observations, instruments, and classification systems. Some older words also have historical meanings that become more precise over time.
Final Takeaway
Space vocabulary becomes easier when you stop treating words as isolated labels.
An orbit is motion. Gravity is an attraction. A nebula is a cloud. An asteroid is a small rocky or metallic body. A comet is an icy body that can become active near the Sun. A meteor is an atmospheric light event. A light-year is distance. A galaxy is a huge gravitational system. The universe is the broadest cosmic whole described in astronomy.
The best beginner habit is to ask:
Is this word describing an object, a place, a movement, a force, a measurement, or a way of observing?
Once you can answer that, space articles become much easier to read. The universe starts to feel less like a wall of strange words and more like a connected map.