Solar System
The planet closest to the Sun
Mercury
This is the name for a huge collection of stars, gas, and dust bound together by gravity
Galaxy
This NASA mission first landed humans on the Moon in 1969
Apollo 11
This term describes the event that marks the beginning of the universe
The Big Bang
This boundary around a black hole marks the point of no return
The event horizon
The gas giant that is famous for its Great Red Spot
Jupiter
Our Sun is classified as this type of star on the Hertzsprung–Russell diagram
A G‑type main‑sequence star (G dwarf)
This space telescope, launched in 1990, has provided deep‑field images of distant galaxies
The Hubble Space Telescope
This mysterious substance makes up about 27% of the universe and interacts through gravity but not light
Dark matter
This type of black hole forms when a massive star collapses under its own gravity
A stellar‑mass black hole
The planet that is tilted about 98 degrees to the Sun
Uranus
This galaxy, visible from Earth, is on a collision course with the Milky Way in about 4 billion years
The Andromeda Galaxy (M31)
This rover, landing in 2012, discovered evidence that Mars once had conditions suitable for microbial life
Curiosity
This radiation, discovered accidentally in 1964, is leftover heat from the early universe
Cosmic microwave background radiation (CMB)
This effect, predicted by Einstein, causes light to bend around massive objects like black holes
Gravitational lensing
This moon of Jupiter is the most volcanically active body in the Solar System
Io
This term describes the explosive death of a massive star
A supernova
This spacecraft, launched in 1977, is now in interstellar space and carries the Golden Record
Voyager 1
This term describes the accelerated expansion of the universe driven by an unknown form of energy
Dark energy
This theoretical radiation, proposed by Stephen Hawking, allows black holes to slowly lose mass over time
Hawking radiation
This resonance between Neptune and Pluto prevents them from ever colliding despite their overlapping orbital paths
A 2:3 orbital resonance (Neptune–Pluto resonance)
This process, occurring in the cores of stars, explains why more massive stars have shorter lifespans despite having more fuel
Nuclear fusion rate scaling (more massive stars burn fuel faster)
This maneuver, used by spacecraft to gain speed, involves using the gravity of a planet to slingshot into a new trajectory
A gravity assist (gravitational slingshot)
This concept describes the idea that the universe’s geometry depends on its total mass‑energy density, determining whether it is open, closed, or flat
The curvature of the universe (open/closed/flat geometry)
This region inside a rotating (Kerr) black hole allows for the possibility of closed timelike curves due to frame dragging
The ergosphere