Which star is at the center of our solar system?
Answer : The Sun
The Sun is the star around which all the planets of our solar system orbit.
Questions and answers: Astronomy
Revise Astronomy: here is a selection of questions of every level, with the answer and an explanation. To test yourself without seeing the answers, play the quizzes.
Play the Astronomy quizzesVery easy
Which planet is closest to the Sun?
Answer : Mercury
Mercury is the closest planet to the Sun in our solar system.
Which natural body orbits the Earth and causes the tides?
Answer : The Moon
The Moon, Earth's natural satellite, influences tides through its gravitational pull.
What do we call a group of stars that forms a recognizable shape in the sky?
Answer : A constellation
A constellation is a group of stars forming a recognizable shape, like the Big Dipper.
Which planet is famous for its rings, visible through a telescope?
Answer : Saturn
Saturn is famous for its ring system, made mostly of ice and rock.
Which celestial event sometimes explodes and temporarily lights up the night sky, visible to the naked eye?
Answer : A supernova
A supernova is the explosion of a dying star, which can shine very brightly.
About how long does it take sunlight to reach Earth?
Answer : 8 minutes
Sunlight takes about 8 minutes to reach Earth.
What is the name of the first permanently inhabited space station currently in orbit?
Answer : The International Space Station
The International Space Station (ISS) has been permanently inhabited in low orbit since 2000.
Easy
Which American astronaut was the first man to walk on the Moon in 1969?
Answer : Neil Armstrong
Neil Armstrong was the first man to walk on the Moon, on July 21, 1969.
Which is the largest terrestrial (rocky) planet after Earth in our solar system?
Answer : Venus
Venus is slightly smaller than Earth but remains the largest terrestrial planet after it.
What type of celestial body is Pluto, since its reclassification in 2006?
Answer : A dwarf planet
Pluto was reclassified as a dwarf planet by the International Astronomical Union in 2006.
Which Italian scientist improved the astronomical telescope and observed Jupiter's moons in the 17th century?
Answer : Galileo
Galileo improved the astronomical telescope and discovered Jupiter's four largest moons in 1610.
Which colorful luminous phenomenon is observed near the poles, caused by the interaction of solar wind with the atmosphere?
Answer : Auroras
Auroras (northern or southern) are caused by the interaction of solar wind with Earth's magnetic field.
Which space telescope, launched in 1990, provided iconic images of the universe for decades?
Answer : The Hubble Space Telescope
The Hubble Space Telescope, launched in 1990, provided many iconic images of the universe.
Which solar system planet rotates almost sideways, tilted nearly horizontally?
Answer : Uranus
Uranus has a highly tilted rotation axis, almost lying on its orbital plane.
What is the name given to a piece of rock that burns up while passing through Earth's atmosphere?
Answer : A meteorite
A meteorite (or meteor during its luminous passage) is a fragment of rock passing through the atmosphere.
Medium
Which Polish astronomer proposed the heliocentric model of the solar system in the 16th century?
Answer : Nicolaus Copernicus
Nicolaus Copernicus proposed the heliocentric model, placing the Sun at the center of the solar system, published in 1543.
Which icy region beyond Neptune is home to Pluto and many other small bodies?
Answer : The Kuiper Belt
The Kuiper Belt is an icy region beyond Neptune containing Pluto and other trans-Neptunian objects.
Which type of extremely dense star results from the gravitational collapse of a massive star?
Answer : A neutron star
A neutron star results from the gravitational collapse of a massive star's core after a supernova.
Which neighboring galaxy will collide with the Milky Way in several billion years?
Answer : The Andromeda Galaxy
The Andromeda Galaxy is on a collision course with the Milky Way, an event expected in several billion years.
Which German physicist formulated the laws of planetary motion in the early 17th century?
Answer : Johannes Kepler
Johannes Kepler formulated three laws describing the orbital motion of planets.
Which NASA probe explored Saturn and its moon system between 2004 and 2017?
Answer : Cassini-Huygens
The Cassini-Huygens probe explored Saturn and its moons from 2004 to 2017.
Which astronomical event occurs when a planet passes directly between its star and an observer, visible as a small dark dot?
Answer : A planetary transit
A planetary transit occurs when a planet passes directly between its star and the observer.
Which famous comet, visible from Earth every 75 to 76 years, is named after an English astronomer?
Answer : Halley's Comet
Halley's Comet, named after Edmund Halley, is visible from Earth about every 76 years.
Hard
Which phenomenon describes the accelerating expansion of the universe, attributed to a still poorly understood energy?
Answer : Dark energy
Dark energy is the name given to the hypothetical cause of the accelerating expansion of the universe.
Which American astronomer discovered in 1929 that galaxies are moving away from each other, evidence of the expanding universe?
Answer : Edwin Hubble
Edwin Hubble demonstrated in 1929 that galaxies are moving away from each other, evidence of the expanding universe.
Which type of celestial object has gravity so intense that not even light can escape it?
Answer : A black hole
A black hole has gravity so intense that no light can escape past its event horizon.
Which radiation, detected in 1965, is major evidence for the Big Bang theory?
Answer : The cosmic microwave background
The cosmic microwave background, detected in 1965 by Penzias and Wilson, is major evidence for the Big Bang.
Which compact binary star, discovered in 1974, allowed indirect confirmation of the existence of gravitational waves?
Answer : The Hulse-Taylor binary pulsar
The Hulse-Taylor binary pulsar, discovered in 1974, allowed indirect confirmation of gravitational waves.
Which mission first directly detected gravitational waves in 2015?
Answer : LIGO
The LIGO observatory first directly detected gravitational waves in September 2015.
Which type of galaxy, like the Milky Way, has a spiral structure with well-defined arms?
Answer : A spiral galaxy
A spiral galaxy, like the Milky Way, has a disk with well-defined spiral arms.
Which ESA space mission precisely maps the position and motion of more than a billion stars?
Answer : The Gaia mission
The European Space Agency's Gaia mission maps more than a billion stars with unprecedented precision.
Expert
Which theoretical limit designates the maximum mass a white dwarf can reach before collapsing?
Answer : The Chandrasekhar limit
The Chandrasekhar limit, about 1.4 solar masses, is the maximum mass of a stable white dwarf.
Which physicist theoretically predicted in 1974 that black holes emit radiation causing them to lose mass?
Answer : Stephen Hawking
Stephen Hawking predicted in 1974 the Hawking radiation, by which black holes gradually lose mass.
Which type of supernova, resulting from the thermonuclear explosion of a white dwarf, serves as a 'standard candle' for measuring cosmic distances?
Answer : A Type Ia supernova
Type Ia supernovae, caused by the thermonuclear explosion of a white dwarf, serve as standard candles in cosmology.
What is the minimum boundary an object must cross near a black hole to no longer be able to escape, even at the speed of light?
Answer : The event horizon
The event horizon, defined by the Schwarzschild radius, is the boundary beyond which nothing can escape a black hole.
Which alternative cosmological theory to the Big Bang, now abandoned, proposed a universe with no beginning or end?
Answer : The steady-state theory
The steady-state theory, notably defended by Fred Hoyle, proposed an eternal universe without a Big Bang, now abandoned.
Which mechanism explains the extremely rapid acceleration of the universe's expansion in its very first fraction of a second?
Answer : Cosmic inflation
Cosmic inflation is the theoretical mechanism of extremely rapid expansion of the universe just after the Big Bang.
Which Indian astrophysicist formulated the limit bearing his name regarding the collapse of stars?
Answer : Subrahmanyan Chandrasekhar
Subrahmanyan Chandrasekhar formulated the Chandrasekhar limit regarding the maximum mass of white dwarfs.
Which nuclear process, occurring in the first minutes after the Big Bang, formed the first light nuclei such as helium?
Answer : Primordial nucleosynthesis
Primordial nucleosynthesis formed the first light nuclei (hydrogen, helium, lithium) in the minutes following the Big Bang.