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← Unit 5: Space Exploration

SNC1W · Unit 5 test review

Space Exploration: Test Review

Everything for the Unit 5 test on one page: the key facts from all 8 lessons, the mistakes that cost the most marks, and a practice test that points you back to the lessons you need.

Key facts

The Sun

  • The Sun is a star: a ball of hot plasma, mostly hydrogen and helium, held together by gravity.
  • Nuclear fusion in the core (about 15 million °C) joins hydrogen nuclei into helium and turns a little mass into a lot of energy.
  • Layers from the centre out: core, radiative zone, convective zone, photosphere (visible surface, about 5500 °C), chromosphere, corona (over 1 million °C).
  • Sunspots are cooler, darker regions caused by strong magnetic fields; their number rises and falls in an 11-year cycle.
  • Flares, CMEs and the solar wind send radiation and charged particles into space and can disrupt satellites, GPS and power grids.
  • Sunlight travels 1 AU ( km) in about 8.3 minutes.

How the Sun Drives Earth's Systems

  • Earth's axis is tilted about 23.4° and points the same direction in space all year.
  • Seasons are caused by the tilt, which changes the angle of sunlight and the length of the day. They are not caused by distance: Earth is closest to the Sun in early January.
  • Noon Sun height at an equinox ; add 23.4° at the June solstice and subtract 23.4° at the December solstice (for places between the Tropic of Cancer and the Arctic Circle, such as southern Canada).
  • Solstices (about June 21 and December 21) have the longest and shortest days; equinoxes (about March 20 and September 22) have about 12 h of day and night almost everywhere.
  • Uneven heating by the Sun drives winds, ocean currents and the water cycle.
  • Auroras form when charged particles from the Sun, guided by Earth's magnetic field, make oxygen and nitrogen in the upper atmosphere glow.

Moon Phases, Eclipses and Tides

  • The Sun always lights half of the Moon; phases show how much of that lit half faces Earth. One full cycle takes about 29.5 days.
  • Phase order: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, waning crescent.
  • Solar eclipse: Sun, Moon, Earth in a line, only at new moon. Lunar eclipse: Sun, Earth, Moon in a line, only at full moon.
  • The Moon's orbit is tilted about 5°, so eclipses happen only a few times a year, not every month.
  • Two tidal bulges give most coasts two high and two low tides about every 24 h 50 min (high tides about 12 h 25 min apart).
  • Spring tides (biggest range) occur at new and full moon; neap tides (smallest range) occur at the quarter moons.

The Solar System

  • Order from the Sun: Mercury, Venus, Earth, Mars, (asteroid belt), Jupiter, Saturn, Uranus, Neptune, (Kuiper belt).
  • A planet orbits the Sun, is nearly round from its own gravity, and has cleared its orbit. A dwarf planet (like Pluto or Ceres) fails the third rule.
  • Terrestrial planets are small, rocky, dense and close to the Sun; giant planets are huge, mostly gas or ice, low in density, with many moons and rings.
  • Asteroids are rocky or metallic; comets are icy and grow a coma and tails that point away from the Sun.
  • Meteoroid (in space) → meteor (streak of light in the atmosphere) → meteorite (reaches the ground).

Distances and Scale in Space

  • Scientific notation: with . Multiply: add exponents. Divide: subtract exponents.
  • 1 AU = average Earth–Sun distance km (about 150 million km).
  • 1 light-year = distance light travels in one year km (about 63 000 AU).
  • Speed of light km/s; time ; sunlight takes about 8.3 min per AU.
  • Scale model: model size real size using the same factor for every size and distance.

Stars, Galaxies and the Universe

  • Star colour shows surface temperature: red is coolest, then orange, yellow, white, and blue is hottest.
  • The H-R diagram plots luminosity against temperature; about 90% of stars lie on the main sequence.
  • Sun-like star: nebula → protostar → main sequence → red giant → planetary nebula → white dwarf.
  • Massive star (over about 8 Sun masses): main sequence → red supergiant → supernova → neutron star or black hole.
  • The more massive a star, the shorter its life.
  • The Milky Way is a barred spiral galaxy about 100 000 ly across; the Sun is about 26 000 ly from its centre. Galaxy types: spiral, elliptical, irregular.

Origin and Evolution of the Universe and Solar System

  • Big Bang theory: about 13.8 billion years ago the universe was extremely hot and dense; space has been expanding and cooling ever since.
  • Redshift: light from distant galaxies is stretched toward red; the farther the galaxy, the bigger the redshift (Hubble's law), so the universe is expanding.
  • The cosmic microwave background is faint microwave radiation from every direction, about −270 °C: leftover heat from the early universe.
  • Nebular hypothesis: about 4.6 billion years ago a spinning cloud of gas and dust collapsed into a disc; the Sun formed at the centre and planets formed in the disc.
  • Rocky planets formed inside the frost line, where it was too hot for ices; giant planets formed beyond it.
  • Two-Eyed Seeing (Etuaptmumk, from Mi'kmaw Elder Albert Marshall) uses the strengths of Indigenous knowledges and Western science together.

Space Exploration and Technology

  • Low Earth orbit (about 160 to 2000 km): the ISS at about 400 km orbits in about 92 minutes. Geostationary orbit (35 786 km): one orbit takes 24 h, so the satellite stays over one spot.
  • The RADARSAT Constellation Mission (three Canadian satellites, 2019) uses radar to see through clouds and darkness, for floods, sea ice, oil spills, ships and crops.
  • Canadian robotics: Canadarm (space shuttle), Canadarm2 and Dextre (ISS); Canadarm3 is being repurposed for lunar surface work.
  • Jeremy Hansen flew on Artemis II (April 2026), the first Canadian to travel around the Moon.
  • A spinoff is a space technology with uses on Earth, such as the neuroArm surgical robot.
  • Space debris travels at about 28 000 km/h in low orbit; sustainable practices include de-orbiting old satellites and removing debris.

Where marks get lost

  • Saying the Sun is "burning" like a fire. There is no combustion; the Sun's energy comes from nuclear fusion of hydrogen into helium. (The Sun)
  • Thinking the surface is the hottest part of the Sun. The core (about 15 million °C) is far hotter than the photosphere (about 5500 °C), and even the corona (over 1 million °C) is hotter than the surface. (The Sun)
  • Calling sunspots holes or cold spots. They are thousands of degrees, just cooler and dimmer than the surface around them. (The Sun)
  • Thinking the Sun is an unusually large or bright star. It is a medium-sized, ordinary star; it only looks so bright because it is much closer than any other star. (The Sun)
  • Believing sunglasses make it safe to look at the Sun. Only certified solar filters or indirect methods like pinhole projection are safe. (The Sun)
  • Saying summer happens because Earth is closer to the Sun. Earth is actually closest in early January, during the Northern Hemisphere's winter. (How the Sun Drives Earth's Systems)
  • Thinking the axis tips back and forth during the year. The axis keeps pointing the same direction in space; it is Earth's position in its orbit that changes which hemisphere leans toward the Sun. (How the Sun Drives Earth's Systems)
  • Thinking the summer solstice is the hottest day of the year. It is the longest day; the warmest weeks usually come later in July and August because land and water take time to heat up. (How the Sun Drives Earth's Systems)
  • Thinking auroras are sunlight reflecting off ice or snow. They are light given off by oxygen and nitrogen atoms hit by charged particles from the Sun. (How the Sun Drives Earth's Systems)
  • Believing solar panels produce nothing on cloudy days. They produce less, but diffuse light still generates some electricity; they produce none at night. (How the Sun Drives Earth's Systems)
  • Thinking Earth's shadow causes the phases. Earth's shadow touches the Moon only during a lunar eclipse; phases come from seeing different amounts of the Moon's sunlit half. (Moon Phases, Eclipses and Tides)
  • Calling the far side of the Moon the "dark side." It gets the same amount of sunlight as the near side; we just never see it from Earth. (Moon Phases, Eclipses and Tides)
  • Thinking spring tides happen only in spring. They happen twice a month, at every new and full moon. (Moon Phases, Eclipses and Tides)
  • Thinking there is only one high tide a day, or that wind causes tides. There are two tidal bulges, so most coasts get two high tides a day, caused by gravity. (Moon Phases, Eclipses and Tides)
  • Mixing up the eclipse orders. In a solar eclipse the Moon is in the middle; in a lunar eclipse Earth is in the middle. (Moon Phases, Eclipses and Tides)
  • Saying Pluto was "removed" from the solar system. It still orbits the Sun; in 2006 it was reclassified as a dwarf planet because it has not cleared its orbit. (The Solar System)
  • Thinking the asteroid belt is crowded like in movies. Large asteroids there are typically hundreds of thousands to millions of kilometres apart, and spacecraft have flown through it safely. (The Solar System)
  • Assuming the closest planet to the Sun is the hottest. Venus is hotter than Mercury because of its thick carbon dioxide atmosphere. (The Solar System)
  • Mixing up meteor and meteorite. A meteor is the streak of light in the sky; a meteorite is the piece that reaches the ground. (The Solar System)
  • Thinking a comet's tail streams out behind it like exhaust. The tails point away from the Sun, so a comet heading back out to space travels tail first. (The Solar System)
  • Treating a light-year as a time. It is a distance: how far light travels in a year (about 9.46 trillion km). (Distances and Scale in Space)
  • Leaving the front number outside 1 to 10, such as . Rewrite it as , adding 1 to the exponent. (Distances and Scale in Space)
  • Adding exponents when dividing. When you divide powers of 10, subtract the exponents; add them only when you multiply. (Distances and Scale in Space)
  • Mixing units in a scale model, such as dividing a distance in km by a size in cm without keeping track. Make sure the units cancel or convert first. (Distances and Scale in Space)
  • Thinking the planets are close together because diagrams show them that way. Most pictures shrink distances far more than sizes; on a true scale the planets are tiny dots far apart. (Distances and Scale in Space)
  • Assuming a brighter-looking star is closer or more powerful. Apparent brightness depends on both luminosity and distance. (Stars, Galaxies and the Universe)
  • Thinking red stars are the hottest because red means hot on a tap. In stars, red is the coolest colour and blue is the hottest. (Stars, Galaxies and the Universe)
  • Saying the Sun will explode as a supernova or become a black hole. It is not massive enough; it will become a red giant and then a white dwarf. (Stars, Galaxies and the Universe)
  • Mixing up solar system, galaxy and universe. The solar system is one star and its planets; a galaxy holds billions of stars; the universe holds all the galaxies. (Stars, Galaxies and the Universe)
  • Thinking a planetary nebula has something to do with planets, or that nebulas only appear at the end of a star's life. Nebulas are also where new stars are born. (Stars, Galaxies and the Universe)
  • Picturing the Big Bang as a bomb exploding into empty space from one spot. It was an expansion of space itself, happening everywhere at once. (Origin and Evolution of the Universe and Solar System)
  • Thinking redshift means a galaxy looks red to the eye. Redshift is a shift of the spectral lines toward longer wavelengths, measured with a spectroscope. (Origin and Evolution of the Universe and Solar System)
  • Using "just a theory" to mean "just a guess." A scientific theory is a well-tested explanation backed by evidence. (Origin and Evolution of the Universe and Solar System)
  • Thinking the Sun formed first and captured the planets later. The Sun and planets formed together from the same spinning disc of gas and dust. (Origin and Evolution of the Universe and Solar System)
  • Treating Indigenous sky knowledge as one single set of stories, or as stories with no observation behind them. Each Nation has its own knowledge, built from generations of careful observation. (Origin and Evolution of the Universe and Solar System)
  • Thinking astronauts float because there is no gravity in space. Gravity at the ISS is about 90% as strong as on the ground; astronauts float because they are in free fall along with the station. (Space Exploration and Technology)
  • Thinking a geostationary satellite is not moving. It moves at about 11 000 km/h, but it keeps pace with Earth's rotation, so it stays above the same spot. (Space Exploration and Technology)
  • Believing Velcro and the drink powder Tang were invented by NASA. Both were invented by others and only later used in space; real spinoffs include phone camera sensors, memory foam and neuroArm. (Space Exploration and Technology)
  • Thinking space exploration only helps astronauts and scientists. Weather forecasts, GPS, disaster maps and climate data help almost everyone. (Space Exploration and Technology)
  • Thinking small bits of space debris are harmless. At about 28 000 km/h even tiny fragments can damage spacecraft. (Space Exploration and Technology)

Practice test

24 questions from across the unit. Each one shows the lesson it comes from.

  1. The Sun
    1
    What process produces the Sun's energy?
  2. The Sun
    2
    Match each feature of the Sun to its description.
    Solar flare
    Prominence
    Solar wind
    Sunspot
    Corona
  3. The Sun
    3
    Which of these is NOT something the Sun provides for life on Earth?
  4. How the Sun Drives Earth's Systems
    4
    What is the main cause of Earth's seasons?
  5. How the Sun Drives Earth's Systems
    5
    Put the steps that produce an aurora in order.
    1. 1The energized atoms give off green, red, blue and purple light
    2. 2The particles collide with oxygen and nitrogen atoms high in the atmosphere
    3. 3Earth's magnetic field guides some particles toward the polar regions
    4. 4The Sun releases charged particles in the solar wind or a coronal mass ejection
    5. 5The particles travel through space and reach Earth
  6. How the Sun Drives Earth's Systems
    6
    Why is wind energy described as an indirect form of solar energy?
  7. Moon Phases, Eclipses and Tides
    7
    What causes the phases of the Moon?
  8. Moon Phases, Eclipses and Tides
    8
    High tides are 12 hours 25 minutes apart. Write this time in hours, to one decimal place.
    h
  9. Moon Phases, Eclipses and Tides
    9
    The lunar cycle lasts about 29.5 days. About how many days pass between new moon and first quarter? Give your answer to one decimal place.
    days
  10. The Solar System
    10
    Put the planets in order from closest to farthest from the Sun.
    1. 1Neptune
    2. 2Uranus
    3. 3Saturn
    4. 4Mercury
    5. 5Venus
    6. 6Earth
    7. 7Mars
    8. 8Jupiter
  11. The Solar System
    11
    Jupiter is 5.20 AU from the Sun. Sunlight takes about 8.3 minutes per AU. How many minutes does sunlight take to reach Jupiter? Round to the nearest minute.
    min
  12. The Solar System
    12
    Saturn is 9.54 AU from the Sun and Earth is 1.00 AU. When both planets are lined up on the same side of the Sun, how far apart are they, in AU?
    AU
  13. Distances and Scale in Space
    13
    A light-year is a unit of…
  14. Distances and Scale in Space
    14
    In a scale model the Sun is a 20 cm ball. The real Sun is km wide and Earth is km from the Sun. How far from the ball should Earth be placed, in metres? Give your answer to one decimal place.
    m
  15. Distances and Scale in Space
    15
    How many astronomical units are in one light-year? Divide km by km and round to the nearest thousand.
    AU
  16. Stars, Galaxies and the Universe
    16
    Which star colour indicates the hottest surface temperature?
  17. Stars, Galaxies and the Universe
    17
    Match each galaxy type to its description.
    Spiral galaxy
    Elliptical galaxy
    Irregular galaxy
  18. Stars, Galaxies and the Universe
    18
    Where were most of the iron atoms in your blood made?
  19. Origin and Evolution of the Universe and Solar System
    19
    What does the redshift of distant galaxies tell astronomers?
  20. Origin and Evolution of the Universe and Solar System
    20
    The universe is about 13.8 billion years old and the solar system about 4.6 billion years old. How old was the universe, in billions of years, when the solar system formed?
    billion years
  21. Origin and Evolution of the Universe and Solar System
    21
    In Ojibwe (Anishinaabe) sky knowledge, what is the Big Dipper part of?
  22. Space Exploration and Technology
    22
    Why can the RADARSAT Constellation Mission map a flood at night under thick clouds?
  23. Space Exploration and Technology
    23
    Put these Canadian space milestones in order from earliest to most recent.
    1. 1The RADARSAT Constellation Mission launches
    2. 2Dextre is launched to the ISS
    3. 3Canadarm2 is installed on the ISS
    4. 4Alouette 1, Canada's first satellite
    5. 5Canadarm first flies on a space shuttle
  24. Space Exploration and Technology
    24
    Which of these is a real environmental cost of space exploration?

Endless drill

Fresh numbers every time, for the calculation questions in this unit.

Endless drillnew numbers every time

Generating a problem…

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