Space & Astronomy

Why B? And why not the others?

Correct answer: B. Jupiter

Jupiter is not just the biggest planet — it is more than twice as massive as all the other planets combined, and about 11 Earths could line up across its face. Its Great Red Spot is a single storm wider than our entire planet. Saturn is a tempting pick because its rings make it look the grandest, but it is the runner-up in size and far lighter. Neptune and Uranus are giants too, yet each is only about four Earths wide — impressive, but a different league entirely.

Source: NASA Science: Jupiter facts (science.nasa.gov/jupiter/jupiter-facts/)

Why D? And why not the others?

Correct answer: D. About 8 minutes

Sunlight crosses the 150 million kilometres (93 million miles) to Earth in about 8 minutes and 20 seconds — so every sunbeam you see left the Sun before you looked up, and we always see the Sun as it was 8.3 minutes ago. Instant arrival feels right because light seems immediate in daily life, but even at 300,000 km per second the gulf of space takes time to cross. Eight seconds hugely underestimates that distance, while eight hours overshoots it — light needs only about five and a half hours to reach even distant Pluto.

Source: NASA Science: Sun facts (science.nasa.gov/sun/facts/)

Why A? And why not the others?

Correct answer: A. Venus

Venus holds the record at about 465 degrees Celsius (870 degrees Fahrenheit) — hot enough to melt lead — because its crushing carbon dioxide atmosphere traps heat in a runaway greenhouse effect. Mercury is the tempting answer since it orbits closest to the Sun, but with almost no atmosphere to hold warmth, its heat escapes and its night side plunges hundreds of degrees below freezing. Mars looks fiery red yet is actually a frigid desert averaging well below zero, and Jupiter's swirling cloud tops are colder still, far out in the dim outer solar system.

Source: NASA Science: Venus facts (science.nasa.gov/venus/venus-facts/)

Why C? And why not the others?

Correct answer: C. Ganymede

Ganymede, orbiting Jupiter, spans about 5,260 kilometres — making it larger than the planet Mercury. It is also the only moon known to generate its own magnetic field, and evidence points to a buried saltwater ocean holding more water than all of Earth's surface oceans. Saturn's Titan is the classic near-miss: it is the second largest and famous for its thick atmosphere, so it often steals the credit. Earth's Moon feels enormous in our sky but ranks only fifth, and Europa, though fascinating for its hidden ocean, is smaller than our Moon.

Source: NASA Science: Ganymede facts (science.nasa.gov/jupiter/jupiter-moons/ganymede/facts/)

Why D? And why not the others?

Correct answer: D. Yuri Gagarin

Soviet cosmonaut Yuri Gagarin became the first human in space on 12 April 1961, circling Earth once aboard Vostok 1 in a flight lasting just 108 minutes — and he parachuted separately from his capsule before it hit the ground. Neil Armstrong is the tempting mix-up because he was the first person to walk on the Moon, but that came eight years later, in 1969. Alan Shepard became the first American in space only weeks after Gagarin, on a short suborbital hop, and John Glenn was the first American to actually orbit Earth, in 1962.

Source: NASA: First Human Entered Space, April 1961 (nasa.gov/image-article/april-1961-first-human-entered-space/)

Why A? And why not the others?

Correct answer: A. Venus

Venus needs 243 Earth days to complete a single rotation but only 225 Earth days to finish a lap around the Sun — its 'day' genuinely outlasts its year. Stranger still, it spins backwards compared with most planets, so from its surface the Sun would rise in the west. Mercury is the tempting near-miss: it is a famously sluggish spinner, yet its 59-day rotation still comfortably beats its 88-day year. Mars is nearly Earth's twin in day length at about 24.6 hours, and Neptune whips around on its axis in roughly 16 hours despite its 165-year orbit.

Source: NASA Science: Venus facts (science.nasa.gov/venus/venus-facts/)

Why C? And why not the others?

Correct answer: C. Mars

Olympus Mons towers about 25 kilometres above the surface of Mars — roughly three times the height of Mount Everest — with a base the size of Arizona. It grew so monstrous because Mars lacks moving tectonic plates: lava kept erupting over the same hotspot for ages, piling ever higher instead of forming a chain of smaller volcanoes as happens on Earth. Io is a clever-sounding trap since it is the most volcanically active body in the solar system, but its eruptions build no giant like this. Venus is dotted with volcanoes too, and Earth's biggest, Mauna Loa, is a fraction of the size.

Source: ESA: Olympus Mons, 25 kilometres high (esa.int) and NASA APOD 2023-04-04: Olympus Mons

Why B? And why not the others?

Correct answer: B. About 99.8 percent

The Sun accounts for about 99.8 percent of the solar system's entire mass — every planet, moon, asteroid, and comet together makes up the remaining sliver, and Jupiter claims most of that. The Sun's interior could swallow more than 1.3 million Earths. Guesses like half or three-quarters feel reasonable because the planets seem so substantial, especially giant Jupiter, yet even Jupiter carries only about a thousandth of the Sun's mass. Even the cautious-sounding 90 percent wildly overrates the planets: in mass terms, the solar system is essentially the Sun plus rounding error.

Source: NASA Science: Solar System facts (science.nasa.gov/solar-system/solar-system-facts/)

Why A? And why not the others?

Correct answer: A. The Moon rotates exactly once for every orbit it makes around Earth

The Moon spins on its axis in the same 27.3 days it takes to orbit Earth, a state called synchronous rotation caused by tidal locking — Earth's gravity gradually braked the Moon's spin until the two motions matched. The idea that the Moon does not rotate is the classic trap: if it truly never turned, we would see every side of it over a month. Calling the far side 'permanently dark' repeats another myth — it receives just as much sunlight as the near side, only during our lunar night. Earth's shadow, meanwhile, touches the Moon only during brief lunar eclipses.

Source: NASA Science: Tidal Locking (science.nasa.gov/moon/tidal-locking/)

Why D? And why not the others?

Correct answer: D. Saturn

Saturn is the only planet in the solar system less dense than water — its average density is about 70 percent that of water — because it is a vast, puffed-up ball of the two lightest elements, hydrogen and helium. Jupiter is the tempting choice since it is made of much the same gases, but its colossal mass squeezes its interior so hard that it ends up denser than water and would sink. Uranus and Neptune sound plausible as gassy outer worlds too, yet they are 'ice giants' rich in heavier water, ammonia, and methane, making both comfortably denser than water.

Source: NASA Science: Saturn facts (science.nasa.gov/saturn/facts/) and Britannica: Saturn