Astrophysics and Dark Matter Quiz

A celestial body that orbits a star, is large enough for its gravity to make it round, and has cleared its orbital path of other objects.

A group of stars that are gravitationally bound together.

A vast collection of stars, gas, dust, and dark matter, all held together by gravity.

A cluster of galaxies that includes the Milky Way and Andromeda.

The average distance between the Earth and the Sun.

The distance that light travels in one year.

An imaginary sphere surrounding Earth, on which all celestial objects appear to be located.

The apparent path of the Sun across the celestial sphere over a year.

Stars appear to rise and set due to the Earth's rotation on its axis. As the Earth spins, different parts of the sky become visible.

Circumpolar stars are stars that appear to circle around the celestial pole and never set below the horizon. This is because they are located close enough to the pole that they remain visible throughout the Earth's rotation.

The Earth's seasons are caused by the tilt of its axis. The tilt causes different hemispheres to receive varying amounts of direct sunlight throughout the year.

The June solstice marks the longest day of the year in the Northern Hemisphere and the shortest day of the year in the Southern Hemisphere. This occurs when the Northern Hemisphere is tilted towards the sun.

The December solstice marks the shortest day of the year in the Northern Hemisphere and the longest day of the year in the Southern Hemisphere. This occurs when the Southern Hemisphere is tilted towards the sun.

Equinoxes occur when the sun is directly over the equator. On these days, all locations on Earth experience 12 hours of daylight and 12 hours of darkness.

The phases of the moon are caused by the changing position of the moon relative to the sun and Earth as it orbits our planet. We only see the illuminated portion of the moon facing us.

The phases of the moon in order are: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent.

Synchronous rotation is the phenomenon where the moon rotates on its axis at the same rate as it revolves around the Earth. This is why we always see the same side of the moon.

Eclipses occur when the Earth, moon, and sun align in a specific way. A solar eclipse happens when the moon passes between the sun and Earth. A lunar eclipse happens when the Earth passes between the sun and moon.

We don't see an eclipse every month because the moon's orbit is tilted slightly in relation to the Earth's orbit around the sun. This means the three bodies don't align perfectly every month.

The geocentric model puts the Earth at the center of the universe, with the sun, moon, and stars orbiting around it. This was a common belief for centuries.

The heliocentric model puts the sun at the center of the solar system, with the Earth and other planets orbiting around it.

Johannes Kepler formulated three laws of planetary motion. His laws state that planets move in elliptical orbits, with the Sun at a focus, the speed of planets varies as they orbit, and the orbital period squared is proportional to the orbital radius cubed.

Good science relies on natural causes, progresses through testing of models, makes testable predictions, and is open to change based on new evidence.

Pseudoscience presents claims or practices that are not supported by scientific evidence. It often lacks testability, relies on anecdotal evidence, and uses misleading terminology.

A mysterious substance that does not interact with light, making it invisible. It accounts for a significant portion of the universe's mass and affects the motion of galaxies and clusters.

Large groups of galaxies bound together by gravity. They contain a significant amount of dark matter, which influences the motion and distribution of galaxies within the cluster.

Distortion of light from distant objects caused by massive objects (like galaxies or galaxy clusters) bending the path of light. This effect can help us detect dark matter.

A mysterious force that is causing the expansion of the universe to accelerate. It is believed to be responsible for the universe's accelerating expansion.

Possible fates of the universe depending on the amount of dark matter and dark energy. Big Crunch: The universe collapses back on itself. Big Freeze: The universe expands forever, becoming cold and empty. Big Rip: The universe expands so rapidly that even atoms are torn apart.

A point of infinite density where all the mass of a black hole is concentrated.

The boundary around a black hole beyond which nothing, not even light, can escape.

Black holes are characterized by their mass, charge, and spin.

Gravitational forces that stretch an object in the direction of a massive object and compress it in the perpendicular direction.

The Milky Way consists of a spiral disk, a central bulge, and an outer halo. Each region has distinct properties in terms of gas content, star formation, age, color, and metallicity.

Earth resides in the Milky Way's spiral disk.

The continuous process of gas flowing through the Milky Way from the halo into the disk, where it fuels star formation and then returns to the halo.

Regions of gas that glow brightly because they are lit up by nearby hot, young stars.

Clouds of dust that reflect light from nearby stars, appearing as blueish or reddish depending on the source of light.

The supermassive black hole at the center of the Milky Way Galaxy.

Sagittarius A* has a mass exceeding 4 million times the mass of our Sun.

The existence and mass of Sagittarius A* are proven by observing the orbits of nearby stars and through direct imaging.

A classification scheme for galaxy morphology, grouping galaxies based on their shape, appearance, and properties.

A series of techniques used to measure distances in the universe, each method building upon the previous one.

Region between Mars and Jupiter containing many rocky objects called asteroids, significantly smaller than Earth's moon. It was once considered a planet before the rest of the asteroid belt was discovered.

Icy region beyond Neptune, similar to the asteroid belt but containing larger objects. Contains dwarf planets like Pluto.

Objects, including Pluto, trapped in a 2:3 orbital resonance with Neptune, meaning their orbits cross but they never collide.

Solid icy body of a comet, usually made of frozen gases, dust, and rock.

Gaseous envelope surrounding the comet's nucleus, created when the ice vaporizes as the comet approaches the Sun.

Dusty and gaseous trails extending from a comet, caused by solar radiation and solar wind.

An event where many meteors (shooting stars) appear in the sky, caused by Earth passing through the orbit of a comet and its debris.

Method for detecting extrasolar planets by directly taking a picture of them, often only feasible for large planets in wide orbits around nearby stars.

Method for detecting extrasolar planets by observing the slight wobble or movement of a star caused by the planet's gravitational pull.

Method for detecting extrasolar planets by measuring the slight shift in the star's light as it is pulled towards and away from Earth by the planet's gravity.

Method for detecting extrasolar planets by observing the slight dimming of a star's light as the planet passes in front of it.

Region around a star where conditions allow liquid water to exist on the surface of a planet, potentially suitable for life.

Balance between the outward pressure of the Sun's hot gas and the inward pull of gravity, maintaining its shape and stability.

Process where lighter atomic nuclei combine to form heavier nuclei, releasing enormous energy, powering the Sun.

Process in the Sun where four hydrogen nuclei (protons) fuse to form a helium nucleus, releasing energy, sustaining the Sun.

Astronauts experience weightlessness in orbit because they are constantly falling around the Earth, but their forward motion prevents them from hitting the ground. This is not due to a lack of gravity.

Tides are caused by the moon's gravitational pull on the Earth's oceans. The pull is stronger on the side of Earth facing the moon, resulting in a bulge of water. The opposite side experiences a weaker pull, resulting in a second tidal bulge.

A spring tide occurs when the Sun, Earth, and Moon align. This creates a stronger gravitational pull and larger tidal ranges.

A neap tide occurs when the Sun, Earth, and Moon form a right angle. This results in a weaker gravitational pull and smaller tidal ranges.

Angular momentum is a measure of an object's tendency to rotate. It is a conserved quantity, meaning it cannot be created or destroyed, it only transferred from one object to another.

Wavelength is the distance between two successive crests or troughs of a wave.

Frequency is the number of wave cycles that pass a given point in a specific time interval, typically measured in Hertz (Hz).

The electromagnetic spectrum encompasses all types of light, ranging from low-energy radio waves to high-energy gamma rays. Visible light is just a small part of this spectrum.

Light travels at a constant speed in a vacuum, and nothing can travel faster. However, light travels slower in other mediums like water or glass.

Kinetic energy is the energy of an object due to its motion. The faster an object moves, the more kinetic energy it has.

Thermal energy is the energy associated with the random motion of atoms and molecules within a substance. It's what we experience as heat.

Gravitational potential energy is the energy stored in an object due to its position in a gravitational field. The higher an object is, the more potential energy it has.

Radiant energy is the energy carried by electromagnetic radiation, like light, infrared, or X-rays.

Wein's Law states that hotter objects emit light with shorter wavelengths and higher frequencies. This means hotter objects emit more blue light.

Emission occurs when a hot object converts thermal energy into radiant energy, releasing light in the process.

Absorption occurs when matter absorbs radiant energy from light, causing the matter to heat up.

Transmission occurs when light passes through matter, like a window, with minimal interaction.

Reflection occurs when light bounces off matter, like a mirror, changing its direction.

Spectra are created when light is split into its individual wavelengths, like a rainbow band. This allows us to analyze the composition and movement of celestial objects.

A continuous spectrum is produced by a hot, dense object and contains all wavelengths of light.

An emission spectrum is produced by a hot gas and only contains specific wavelengths of light corresponding to the elements present in the gas.

An absorption spectrum is created when light from a hot, dense object passes through a cooler gas. The gas absorbs specific wavelengths of light, leaving dark lines in the spectrum.

The Doppler Effect explains the change in the observed frequency (or wavelength) of light or sound waves due to the relative motion between the source and the observer.

Blueshift occurs when an object is moving towards us, causing its light waves to be compressed, resulting in a shift towards shorter wavelengths, appearing bluer.

Redshift occurs when an object is moving away from us, causing its light waves to be stretched, resulting in a shift towards longer wavelengths, appearing redder.

Spectral line broadening occurs when an object is rotating, causing the spectral lines to widen because different parts of the object are moving towards or away from us at different speeds.

The atomic number of an element is the number of protons in the nucleus of an atom.

The atomic mass number of an element is the total number of protons and neutrons in the nucleus of an atom.

Refraction is the bending of light as it passes from one medium to another, such as from air to water.

Lenses are transparent materials that refract light to focus it at a specific point called the focal point.

Angular resolution is a telescope's ability to distinguish fine details, measured by the smallest angle between two objects that can be seen as separate.

Light gathering area is a telescope's ability to collect light from faint objects. Larger telescopes have a greater light gathering area and can see fainter objects.

Magnification is a telescope's ability to make an object appear larger than it actually is.

A refracting telescope uses lenses to focus light and create an image, similar to how the human eye works.

A reflecting telescope uses mirrors to focus light and create an image. Most large telescopes are reflecting telescopes.

Good astronomical observing sites are dark, high altitude, calm, and dry to minimize light pollution, atmospheric blurring, and cloud cover.

Earth's atmosphere allows some wavelengths of light to pass through, like visible light, but others are absorbed or scattered, such as X-rays and gamma rays. This limits observations from Earth.

The solar system consists of one star, eight planets, dwarf planets, moons, asteroids, and comets.

The inner solar system contains smaller, rocky objects, while the outer solar system contains larger, icy objects. Planets in the solar system generally orbit in the same direction the Sun spins.

This hypothesis, now falsified, proposed that planets formed from material ripped from the Sun during a close encounter with another star.

The solar system formed from a collapsing cloud of gas and dust called a nebula. Most of the mass went to the Sun, with the rest forming planets, asteroids, and other objects.

The distance from the Sun where hydrogen-based compounds like water can freeze. Objects inside the frost line are rocky, while objects outside have icy cores.

Early, small, rocky or icy bodies that collided and grew into planets.

A period early in the solar system where many planetesimals collided with planets, creating craters.

The Moon formed from a collision between Earth and a Mars-sized object.

Venus has a thick, mostly carbon dioxide atmosphere, likely formed when its oceans evaporated, releasing water vapor and carbon dioxide.

Dark regions on the Moon's surface, filled with volcanic plains.

Mars has features like canyons and dried-up riverbeds, suggesting that liquid water once flowed on its surface.

A giant, long-lived storm system in Jupiter's atmosphere, similar to a hurricane.

Saturn's rings are composed of ice and rock particles, likely formed from shattered moons or ejected material from its moons.

Ice giants, with atmospheres mostly composed of methane, giving them a blue appearance.

Icy objects that orbit the Sun and develop a coma and tails as they get closer.

Finding planets around other stars by taking a direct image of the planet, challenging but more common for large, distant planets.