Solar System

Solar System in 2027 is about habitability: where in our Solar System and around other stars liquid water, energy and the right chemistry could come together, and how we would know. You will be shown an image of an icy moon, a spectrum, a light curve or a mission diagram and asked what it shows, which process made it, and what it means for life. Calculators are not allowed, so every number must come from algebra, ratios and careful estimation. Strong teams can explain why Europa may hold an ocean despite sitting far outside the Sun's habitable zone, how a plume sample from Enceladus tells us about chemical energy, and what a transit depth reveals about a TRAPPIST-1 planet, each in a few precise sentences.

Event format

Two sheets used on both sides give you four pages. That is enough for the formulas in this guide, a one-line card for each named object and mission, a table of the three exoplanet systems and a short list of biology terms. Lay them out so you can find any item in a few seconds.

What the rules cover

The 2027 rules (Solar System B, section 3) combine a list of named worlds with six topic areas. The table paraphrases every item; the numbers match the section numbers in the 2027 rules manual.

Archived tests come from earlier themes, so many old prompts are about objects that are no longer listed. Use them for general skills (reading images, Kepler's laws, detection methods) and spend most of your study time on the lists above.

Conditions for habitability

Life as we know it needs three things at once: liquid water as a solvent, a usable energy source, and the right chemical elements, especially carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur (CHNOPS). A fourth requirement is time: the environment must stay stable long enough for chemistry to become biology. Every condition in the rules is a way of asking whether a world meets these needs.

Temperature and the habitable zone

The habitable zone (sometimes called the Goldilocks zone) is the range of distances from a star where a planet with an Earth-like atmosphere could keep liquid water on its surface. Its location depends on the star's luminosity: a dim red dwarf has a habitable zone a few hundredths of an AU from the star, while the Sun's runs from roughly 0.95 to 1.7 AU depending on the model used. Venus sits inside the inner edge and Mars near the outer edge.

The habitable zone is a surface concept. Europa, Enceladus, Ganymede and Titan all lie far outside it, yet each probably hides a liquid-water ocean beneath ice. Their heat comes from tides and radioactive decay, not sunlight. That is the central idea of the 2027 theme: habitability can extend well beyond the habitable zone.

Atmospheres: composition and retention

An atmosphere does three jobs for habitability. It raises surface pressure, which lets water stay liquid instead of boiling off; it traps heat through the greenhouse effect; and it shields the surface from some radiation. Whether a world keeps its atmosphere depends on a competition between gravity and the speed of gas molecules.

Gas molecules move faster when they are hot and when they are light. If a significant fraction of molecules in the upper atmosphere move faster than the escape speed, the gas leaks away over time (thermal or Jeans escape). A common rule of thumb is that a gas survives for billions of years if the escape speed is at least about six times the molecules' typical thermal speed.

Escape is not only thermal. The solar wind can strip ions from an upper atmosphere that is not protected by a global magnetic field. This is how Mars lost much of its air, as MAVEN measured. Venus, also without an internal magnetic field, lost its water instead: sunlight split water molecules, and the light hydrogen escaped to space.

Stable liquids, surface and subsurface

Liquid water needs the right temperature and pressure. On a phase diagram, every substance has a triple point below which the liquid cannot exist at any temperature. For water that point is about 0.006 bar and 273 K. Mars's average surface pressure, about 0.006 bar, sits right at that limit, which is why pure liquid water is not stable on the Martian surface today: it freezes or boils away quickly.

Underground, the picture changes. An ice shell acts as an insulating lid and supplies pressure, so water beneath it can stay liquid for billions of years if there is enough internal heat. Dissolved salts and ammonia lower the freezing point further, which is why models of Titan's ocean include ammonia. A subsurface ocean is shielded from radiation and impacts, but it is also hidden, so we infer it from magnetic fields, gravity, rotation wobbles and plumes.

Titan is the one world besides Earth with stable surface liquids. Its lakes and seas are liquid methane and ethane, not water, at about 94 K.

Tidal heating

Tidal forces come from the difference in gravity across a body: the near side of a moon is pulled harder than the far side, which stretches the moon along the line to its planet. If the moon's orbit is slightly eccentric, its distance to the planet changes during each orbit, so the stretch rises and falls. That repeated flexing produces friction inside the moon and turns orbital energy into heat.

Tidal heating keeps going only if something keeps the orbit eccentric. For Jupiter's moons that something is an orbital resonance: Io, Europa and Ganymede have periods close to a 1:2:4 ratio (the Laplace resonance), so their regular tugs on one another stop the orbits from becoming circular. Enceladus is in a 2:1 resonance with Saturn's moon Dione, which plays the same role.

Chemical disequilibrium

Life needs an energy source, and in the dark that source is chemistry. A mixture of chemicals that would react and release energy, but has not yet done so, is in chemical disequilibrium. Organisms make their living by speeding up those reactions and keeping some of the energy. On Earth's seafloor, microbes combine hydrogen from hot rock with carbon dioxide to make methane (methanogenesis), harvesting the energy released.

Disequilibrium matters in two directions. In an ocean, it is food: Enceladus's plumes contain molecular hydrogen and carbon dioxide together, an energy source microbes could use. In an atmosphere, it can be a biosignature: Earth's air holds oxygen and methane together even though they react with each other, because life keeps producing both. A planet whose atmosphere is far from equilibrium is a candidate for life, though non-biological explanations must always be ruled out.

Geologic and chemical evidence

Reading past water from landforms

Running water leaves shapes that wind and lava rarely make. Learn to name these and say what they imply.

Mars has all of these. Jezero crater, Perseverance's landing site, holds a delta built into an ancient lake, which made it a prime place to search for preserved signs of past life. On icy moons, the "water" evidence looks different: chaos terrain on Europa, where blocks of ice have broken apart and refrozen, suggests liquid water or slush close to the surface.

Crater counts give a relative age: a surface with few craters has been resurfaced recently. Europa and Enceladus have very few craters on parts of their surfaces, which points to ongoing activity. Venus also has relatively few craters, spread evenly, which suggests the whole surface was repaved by lava within roughly the last billion years.

Reading composition from spectra

Molecules absorb light at specific wavelengths that match their vibrations. A reflectance spectrum shows how much light a surface reflects at each wavelength; dips called absorption bands identify the material. Water ice has bands near 1.5 and 2.0 µm; hydrated clays show features near 1.9 and 2.3 µm; carbon dioxide has a strong band near 4.3 µm. The shape of the ice bands even tells crystalline ice from amorphous ice.

For atmospheres, you can see absorption in two ways. In transmission spectroscopy, starlight passes through a transiting planet's atmosphere, and molecules make the planet look slightly larger at the wavelengths they absorb. In emission spectroscopy, you measure the planet's own thermal glow, for example by comparing light just before and during a secondary eclipse, when the planet passes behind its star.

Delivery by small bodies

Earth formed inside the snow line, where the young disk was too warm for water ice to condense easily, so much of its water and organic material may have arrived later on asteroids and comets. Two named small bodies test this idea.

The test uses the deuterium-to-hydrogen (D/H) ratio. Deuterium is a hydrogen isotope with one neutron in its nucleus. Water that formed in colder parts of the early disk tends to be richer in deuterium, so D/H acts as a fingerprint of where water came from. Rosetta measured comet 67P's water at roughly three times Earth's ocean D/H ratio, which argues against comets like it being the main source of Earth's water. Carbon-rich asteroids have D/H values much closer to Earth's, so asteroids like Bennu are currently favored as major contributors.

Biology and chemistry of life

Building blocks of life

Phosphorus is a common bottleneck: it sits in the backbone of DNA and RNA and in ATP. Its detection as phosphates in Enceladus's plume grains, reported in 2023, removed one objection to that ocean's habitability. Silicon is sometimes proposed as an alternative to carbon, but silicon forms fewer stable chains and its oxide is a solid (rock) rather than a gas, so carbon remains far more versatile.

Phases and forms of water

Extremophiles

Extremophiles are organisms that thrive in conditions once thought too harsh for life. They define the limits we use to judge other worlds.

• Chemolithoautotrophs get energy from inorganic chemical reactions (litho, rock) and build their bodies from carbon dioxide (autotroph). Methanogens at hydrothermal vents are the standard example, and they are the model for life in Enceladus's or Europa's ocean, where no sunlight reaches.
• Tardigrades are tiny animals that survive drying out by entering a dormant "tun" state. In that state they have survived vacuum and radiation, including exposure in space. They show how life can endure, though they cannot grow, in harsh conditions.
• Thermophiles grow best above about 45 °C, and hyperthermophiles above about 80 °C; psychrophiles grow near or below 0 °C; halophiles need very salty water; acidophiles live in strong acid; radiation-resistant microbes repair badly damaged DNA. Each matches a planetary setting: hot vents, icy brines, salt deposits, Venus's acidic clouds, a radiation-blasted surface.

The named Solar System worlds

Questions should focus here. For each world, know the evidence for liquids, the energy source and the main obstacle to life.

Venus

Venus is Earth-sized but hostile. Its atmosphere is about 96% carbon dioxide with a surface pressure about 90 times Earth's, and its surface sits near 737 K, hotter than Mercury's, under clouds of sulfuric acid droplets. Venus likely had more water early on. As the young Sun brightened, water vapor, a greenhouse gas, built up and warmed the planet further, which put more water in the air in a runaway greenhouse. Sunlight split the water, hydrogen escaped, and the evidence remains: Venus's D/H ratio is roughly 100 times Earth's, because the lighter hydrogen escaped more easily and left deuterium behind.

The surface winds are slow, but the cloud tops race around the planet in about four days, far faster than Venus's own 243-day rotation (superrotation). About 50–60 km up, the temperature and pressure are close to Earth's surface values, which is why some researchers have suggested the clouds as a niche for microbes, though the acidity and dryness make that hard. A 2020 claim of phosphine in the clouds as a possible biosignature remains disputed. Venus also has volcanoes, and evidence from Venus Express and later analysis of Magellan radar suggests some are still active.

Mars

Mars is the best-studied candidate for past life. Its surface records rivers, lakes, deltas and minerals formed in water, mostly more than 3 billion years old. Since then Mars has lost most of its atmosphere: today's air is about 95% carbon dioxide at under 1% of Earth's pressure, and the mean surface temperature is near 210 K. Two reasons combine. Mars is small, so it lost internal heat quickly and its global magnetic field shut down, leaving the upper atmosphere exposed to the solar wind; and its low gravity makes escape easier.

Without a thick atmosphere or magnetic field, the surface receives harsh radiation, and perchlorate salts in the soil are toxic to many microbes. The best places to look for life are underground, or in ancient rocks that preserved organic matter. Methane has been detected at low and varying levels, which could come from geology or biology; that debate is open.

Ganymede

Ganymede is the largest moon in the Solar System, wider than the planet Mercury, and the only moon known to make its own magnetic field, a discovery by Galileo. Its subsurface ocean was supported by Galileo's magnetometer and by Hubble observations of its aurorae, which shifted less than expected because a salty, electrically conducting ocean resists changes in Jupiter's field. Ganymede is so large that high pressure may form dense ice below the ocean, which could seal the water off from the rocky mantle. Without contact with rock, the water receives fewer minerals and less chemical energy, which makes Ganymede a weaker habitability candidate than Europa. JUICE will orbit Ganymede in the 2030s.

Europa

Europa has a young, bright ice shell crossed by long ridges and broken by chaos terrain, with few craters. Beneath an ice shell several to tens of kilometers thick lies a global salty ocean, inferred from the magnetic field Galileo measured: Jupiter's field changes as seen from Europa, and a conducting ocean produces an induced magnetic field in response. The ocean likely touches a rocky seafloor where water–rock reactions could supply hydrogen and minerals. At the surface, Jupiter's radiation splits ice into oxidants such as oxygen and hydrogen peroxide; if those reach the ocean, they pair with seafloor chemistry to create chemical disequilibrium.

Enceladus

Enceladus, only about 500 km across, is the best place in the Solar System to sample an ocean directly. In 2005 Cassini found jets of water vapor and ice grains erupting from four warm fractures near its south pole, nicknamed the tiger stripes. This is cryovolcanism: eruption of water and volatiles instead of molten rock. The plume material feeds Saturn's faint E ring.

Cassini's flights through the plume found salts, so the water has touched rock; tiny silica grains that likely form in water above about 90 °C, pointing to hydrothermal activity on the seafloor; molecular hydrogen alongside carbon dioxide, a source of chemical energy for methanogens; organic molecules; and, in later analysis of ring grains, phosphates. A small libration (wobble) in Enceladus's rotation showed the ice shell floats on a global ocean rather than a local sea. Enceladus therefore has all three requirements: liquid water, energy and the key elements.

Titan

Titan, Saturn's largest moon, has a thick nitrogen atmosphere with a few percent methane, a surface pressure about 1.5 times Earth's and a temperature near 94 K. Sunlight breaks up methane high in the atmosphere, and the fragments combine into an orange organic haze; heavier organics settle out as dunes of organic sand. Methane plays the role water plays on Earth: it forms clouds, rains, carves river channels and fills lakes and seas near the poles, such as Kraken Mare and Ligeia Mare. Because sunlight destroys methane over time, something must resupply it, possibly outgassing from the interior or from clathrates in the crust.

Below the surface, Titan likely has a water–ammonia ocean. Titan therefore offers two kinds of habitability question: could life use liquid methane as a solvent at the surface (an open question, since reactions are very slow at 94 K), and could the deeper water ocean support familiar biology? Huygens landed on Titan in 2005, and Dragonfly will explore its organic dunes and an impact crater where melted water may once have mixed with organics.

Makemake

Makemake is a dwarf planet in the Kuiper Belt, roughly 1,400 km across, orbiting the Sun about every 300 years. Its reddish surface is dominated by methane ice, with ethane and other hydrocarbons produced when radiation processes that ice. A 2011 stellar occultation found no substantial global atmosphere, and a small dark moon was discovered in 2016. Makemake is an end member for habitability: so cold and so far from the Sun that liquid water is very unlikely. It is still worth studying because JWST spectra of its methane, including its D/H ratio, have been interpreted as hints that some methane may come from internal geochemistry rather than only ancient ice, so even small cold worlds may have had warm interiors.

101955 Bennu

Bennu is a small (about 500 m across), dark, carbon-rich near-Earth asteroid shaped like a spinning top. It is a rubble pile: loose fragments held together by weak gravity, with a bulk density only about 1.2 g/cm³, so much of its volume is empty space. OSIRIS-REx touched its surface in 2020 and found it behaved almost like a pit of loose gravel; the sample capsule landed in Utah in September 2023.

The samples contain minerals formed in water, such as clays and carbonates, salts that look like evaporated brine, ammonia, and organic molecules including amino acids and all five nucleobases used in DNA and RNA. Bennu's parent body once had liquid water, and asteroids like it could have delivered the ingredients of life to the early Earth. The samples do not contain life; they contain its building blocks.

67P/Churyumov–Gerasimenko

Comet 67P is a Jupiter-family comet about 4 km long, shaped as a contact binary: two lobes joined at a narrow neck. Rosetta orbited it from 2014 to 2016, watching it grow active as it neared the Sun, and the Philae lander touched down in 2014, bouncing before settling in a shadowed spot. Rosetta found the high D/H ratio described above, the amino acid glycine, phosphorus, many organic molecules and, surprisingly, molecular oxygen, which suggests some ices are older than the Solar System. Comets show that the raw materials of life are widespread, even if 67P-like comets were not the main source of Earth's oceans.

The extrasolar systems

The rules name three systems. Each is a different kind of habitability target.

TRAPPIST-1 is the richest Earth-sized system known. Its seven planets orbit in 1.5 to 19 days in a chain of resonances, so they tug on one another and their transits arrive slightly early or late. Because the star is dim, the habitable zone sits a few hundredths of an AU out, and planets there are probably tidally locked, with one side always facing the star. Red dwarfs also flare strongly when young, which can strip atmospheres. JWST measured the thermal glow of the two innermost planets and found no sign of a thick carbon-dioxide atmosphere, so whether the habitable-zone planets kept air is a key open question.

Kepler-452b was announced in 2015 as a near "Earth cousin": a planet in the habitable zone of a Sun-like star, with a year only about 5% longer than ours. Its star is older and slightly brighter than the Sun, so the planet receives about 10% more energy than Earth. Its mass has never been measured because the star is too faint and distant for radial velocity, so we do not know if it is rocky. Later re-analysis of Kepler data even questioned how securely the planet is confirmed, so state its status carefully.

LHS 1140 b is a favorite JWST target because it transits a nearby, quiet red dwarf, and its mass and radius are both measured. Combining them gives a density lower than a pure-rock planet of that size, which suggests a large fraction of water: possibly a water world, perhaps with a liquid ocean on its day side if it has an atmosphere. It shows why combining two detection methods matters.

Light, temperature and the math of habitability

Blackbodies

A hot object emits a continuous spectrum. Wien's displacement law gives its peak wavelength, and the Stefan–Boltzmann law gives the power emitted per square meter.

Flux, albedo and equilibrium temperature

Starlight spreads over a sphere as it travels, so the flux (power per square meter) falls with the inverse square of distance. A planet absorbs the fraction $(1 - A)$ of the light hitting it, where albedo A is the fraction reflected. Balancing absorbed sunlight against emitted infrared gives the equilibrium temperature, the temperature without any greenhouse effect.

Doppler shift

Gravity, orbits and energy

Kepler's first law says orbits are ellipses with the star at one focus; the second says a planet sweeps equal areas in equal times, so it moves fastest when closest to the star; the third relates period to orbit size. Escape speed comes from setting kinetic energy equal to the depth of the gravitational potential well: $\tfrac{1}{2}mv^2 = GMm/R$ gives $v_{\text{esc}} = \sqrt{2GM/R}$. Deriving equations like this is exactly what the rules ask for.

Exoplanet detection

The 2027 rules limit detection to four methods. Each measures a different signal and favors different planets.

Transits

Radial velocity

Microlensing

Mass bends light. When a foreground star passes almost exactly in front of a more distant star, its gravity acts as a lens and the background star brightens and then fades over days to weeks in a smooth, symmetric curve. If the lens star has a planet, the planet's own gravity can add a short extra spike or bump lasting hours to days.

Microlensing does not need light from the planet or even much light from the lens star, so it finds planets thousands of light-years away, cold planets a few AU from their stars (the region where transits and radial velocity struggle), and even planets with no star at all. Its drawback is that each alignment happens only once, so there is no follow-up. Surveys watch dense star fields such as the galactic bulge, which is the job of the Roman Space Telescope.

Direct imaging

A Sun-like star outshines a Jupiter-like planet by about a billion times in visible light. Imaging works best in the infrared, where young, hot planets glow, and for planets far from their stars. A coronagraph blocks the star's light inside the telescope; a starshade would do it from outside. Direct imaging is the method that could one day take spectra of an Earth-like planet's atmosphere and look for biosignatures, and Roman carries a coronagraph to test the technology.

Missions and telescopes

The 2027 rules allow specific questions only about the 16 missions below. For each, know the target, the key instruments and the engineering tradeoff it illustrates.

Design tradeoffs

The rules ask for engineering principles, so tie each design choice to a constraint.

Power. Sunlight falls with the inverse square of distance. At Jupiter (5.2 AU) it is about $1/5.2^2 \approx 1/27$ as strong as at Earth, and at Saturn (9.5 AU) about 1/90. Europa Clipper and JUICE therefore carry very large solar arrays. Galileo and Cassini used radioisotope thermoelectric generators (RTGs), which turn heat from radioactive decay into electricity. Dragonfly also uses one, because Titan is both distant and hazy, so little sunlight reaches the surface.

Radiation. Jupiter's magnetic field traps intense radiation near Europa. Clipper protects its electronics in a shielded vault and stays in a long, looping Jupiter orbit, diving past Europa and then retreating, rather than orbiting Europa and taking a lethal dose.

Planetary protection. Galileo and Cassini were deliberately crashed into their planets at the end of their missions so they could never contaminate Europa, Enceladus or Titan with Earth microbes. Mars landers are cleaned for the same reason.

Getting down. Venus's crushing, hot atmosphere means a probe like DAVINCI does most of its science during descent. Titan's thick air and low gravity favor parachutes and flight. Mars's thin air is the hardest case: too thin to slow a lander fully, so Perseverance needed a heat shield, a parachute and a rocket-powered sky crane.

Orbiters, landers and flybys. Orbiters map whole worlds and watch change over time; landers and rovers analyze rocks directly but see one place; flybys are cheaper but brief. Sample return, as with OSIRIS-REx, lets laboratories on Earth use instruments too large to fly.

Telescopes. The diffraction limit sets the smallest resolvable angle, $\theta \approx 1.22\,\lambda/D$, so bigger mirrors resolve finer detail and collect more light (area grows as $D^2$). Infrared telescopes must be cold so their own heat does not swamp the signal, which is why JWST sits behind a five-layer sunshield at L2. Roman's mirror is the same size as Hubble's, but its camera covers a field about a hundred times larger, trading fine detail for the huge sky coverage that a microlensing survey needs. Kepler similarly stared at one patch of sky for years because transits are rare and brief.

Math without a calculator

The 2027 rules say questions must not need a calculator and should stress algebra, estimation, dimensional analysis, graph sketching and proportions.

Turn formulas into proportions. Write the dependence, then plug in a ratio. $T_{\text{eq}} \propto d^{-1/2}$: four times farther is half the temperature. $j \propto T^4$: twice as hot radiates 16 times more. $a_{\text{tide}} \propto d^{-3}$: twice as close gives 8 times the tide. $P \propto a^{3/2}$: four times the orbit size gives 8 times the period.

Know a small table. $\sqrt{2} \approx 1.41$, $\sqrt{3} \approx 1.73$, $\sqrt{10} \approx 3.16$, $2^{1/4} \approx 1.19$, $\ln 10 \approx 2.3$, $\pi \approx 3.14$, $4\pi \approx 12.6$. A fourth root is a square root of a square root.

Check units. Dimensional analysis catches errors fast: $\sqrt{GM/R}$ must come out in m/s, and $kT$ must be in joules. Always use kelvin in the Stefan–Boltzmann law, Wien's law, the ideal gas law and the Arrhenius equation.

Sketch graphs. Know the shapes: flux versus distance is a steep $1/d^2$ curve; a blackbody curve rises sharply, peaks and falls with a long tail, and the peak moves left as temperature rises; a transit is a flat-bottomed dip; a radial-velocity curve is a sine wave for a circular orbit; a microlensing event is a smooth symmetric peak.

Strategy

Split by strength, then check each other. One partner takes the math, detection methods and missions; the other takes the named worlds, evidence for water, and biology and chemistry. Swap at the end to check algebra, because a wrong power of ten is the most common way to lose points you had earned.

Build the sheets around the lists. One row per named world (liquids, energy source, obstacle, key mission), one per extrasolar system, one per mission, and every formula in this guide with its units. Put the small math table in a corner.

Read every image the same way. Find the scale, name the feature, state the process, then say what it means for habitability. That last sentence is often what separates full credit from partial.

Take the quick points first. Fifty minutes is short. Answer identification items fast, mark long derivations, and come back. Show steps on every calculation, since scoring rewards quality.

Practice without a calculator. Do at least three timed sets by hand and note where you reached for a button.

Common pitfalls

How tournaments test this

The site's archive holds 1,169 Solar System questions from five seasons (2018, 2019, 2022, 2023 and 2024), all Division B. The question bank has 6,377 more. These come from earlier themes, so their named lists differ from 2027, but their format and favorite skills carry over.

Format. Free response dominates: 71.8% of archived questions (839) are free response, 20.2% multiple choice (236), 3.9% multiple select (46), 2.6% true or false (30) and 1.5% numeric (18). Prepare to write explanations, not just pick letters.

Subtopics. Surface features is the largest tag (23.7% of archived questions), followed by Solar System objects (19.5%), spacecraft and telescopes (17.9%), detection techniques (17.8%), orbital mechanics (17.1%) and atmospheric features (17.1%). All of these remain central in 2027, now framed around habitability.

Task types. The most common demand is to explain why (13.2%), then "which of the following" items (7.9%) and interpreting data from a graph, table or curve (3.6%). The 2027 rules put more weight on math and data interpretation than older tests did, so expect more derivations and figures.

Recurring terms and answers. Venus is the most common correct answer in the archive and bank (42 questions), and Mars (25) and Titan (20) are close behind. "Habitable zone" already appears in 49 prompts, "radial velocity" in 80, "transit method" in 38 and "direct imaging" in 35. Expect older prompts on exoplanet detection and on Venus, Mars and Titan to remain useful practice.

Where to practice. The most-represented archived tournaments are Rickards SO Invitational (2023, 101 questions), Garnet Valley Invitational (2019, 94) and University of Texas at Austin Regional (2019, 80). Of all archived questions, 444 (38.0%) meet the site's rule for trusting the answer key; the quizzes below come from that subset and were chosen for 2027 scope.

Test yourself

These are real tournament items, re-solved for this guide and chosen because their content falls inside the 2027 rules. Try each before reading the explanation.

Test yourselfVenus, Mars and Titan

0 / 0 correct

1. 1

   For the following characteristics, list Venus or Mars in order. a. Larger diameter b. Smaller relative mass c. Shorter period of rotation d. Denser, on average e. More spherical f. More moons

   Question 1 options

   AVenus, Mars, Mars, Venus, Venus, MarsBVenus, Venus, Mars, Mars, Venus, MarsCMars, Venus, Mars, Venus, Venus, MarsDMars, Mars, Venus, Venus, Venus, Mars

   From: BullSO Invitational, 2022-23, Division B

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Test yourselfHabitability, small bodies and exoplanets

0 / 0 correct

1. 1

   What term is used to describe the area around a particular star in which a planet could theoretically support life?

   Show answer

   From: Rickards Mini Invitational, 2021-22, Division B

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References and further reading

• Science Olympiad (soinc.org): the 2027 rules manual and any official clarifications.
• SciOly Wiki, Solar System: community notes on the event. Link only.
• NASA Science: Solar System: pages for Venus, Mars, Europa, Enceladus, Ganymede, Titan, Makemake, Bennu and comets.
• NASA Astrobiology: habitability, biosignatures and extremophiles.
• NASA Exoplanet Exploration: detection methods and the TRAPPIST-1, Kepler-452 and LHS 1140 systems.
• NASA Exoplanet Archive: planet and star parameters for the three named systems.
• NASA planetary fact sheets: masses, radii, distances and albedos used in the worked examples.
• ESA Rosetta, ESA JUICE and ESA Venus Express: mission pages.
• NASA Europa Clipper, Dragonfly, OSIRIS-REx and Roman Space Telescope: mission pages.
• OpenStax, Astronomy 2e: free chapters on planetary atmospheres, icy moons, small bodies, exoplanets and life in the universe.