Bell Ringers: Earth’s Place in the Universe

For optimal viewing experience, it is recommended to access this page on a computer or large tablet.

Earth-Sun-Moon System

Use the arrows located at the bottom of the presentation to navigate through all the bell ringer questions.

  1. Misconception: The phases of the moon are caused by Earth’s shadow falling on the moon.
    • Clarification: The phases of the moon are caused by the changing relative positions of the Earth, moon, and sun. Earth’s shadow causes lunar eclipses, not the moon’s phases.
  2. Misconception: The dark side of the moon is always dark.
    • Clarification: There is no permanently dark side of the moon. Every part of the moon gets sunlight half of the time. The side of the moon that is not visible from Earth is often referred to as the “dark side,” but it receives just as much sunlight as the side facing us.
  3. Misconception: Solar eclipses occur every new moon, and lunar eclipses occur every full moon.
    • Clarification: Eclipses don’t happen every month because the moon’s orbit is tilted relative to Earth’s orbit. This means the three bodies usually don’t align perfectly to produce an eclipse.
  4. Misconception: Seasons are caused by Earth’s varying distance from the sun.
    • Clarification: Seasons result from the tilt of Earth’s rotational axis away or toward the sun as it orbits the sun. It’s not about how close Earth is to the sun but rather the angle at which sunlight hits the Earth.
  5. Misconception: The Earth is at the center of the Earth-sun-moon system.
    • Clarification: The sun is at the center of our solar system, and both Earth and the moon revolve around it. The moon, in turn, orbits around Earth.
  6. Misconception: During a solar eclipse, the moon completely disappears.
    • Clarification: During a solar eclipse, the moon passes between Earth and the sun, causing a shadow to fall on Earth. It’s the sun that is obscured, not the moon.
  7. Misconception: The same side of the moon is in darkness throughout its monthly cycle.
    • Clarification: All parts of the moon experience day and night just like Earth. We always see only one side of the moon from Earth due to synchronous rotation, but both sides experience light and dark periods.
  8. Misconception: Eclipses are rare events.
    • Clarification: Eclipses are relatively frequent, with at least two solar eclipses occurring somewhere on Earth each year. However, seeing an eclipse from any given location on Earth is less common.
  9. Misconception: The north pole always points towards the same star.
    • Clarification: While the North Star (Polaris) is currently aligned closely with Earth’s axis of rotation, this changes over time due to axial precession. Over long periods, different stars serve as the North Star.
  10. Misconception: The moon doesn’t rotate.
  • Clarification: The moon does rotate on its axis, but its rotational period matches its orbital period around Earth. This is called synchronous rotation, which is why we always see the same face of the moon.

Role of Gravity in the Motions within Galaxies and the Solar System​

Use the arrows located at the bottom of the presentation to navigate through all the bell ringer questions.

  1. Misconception: Objects in space are weightless because there is no gravity.

    • Clarification: Objects in space (like astronauts in the International Space Station) appear weightless because they are in free fall around the Earth. Gravity is still at work; it’s what keeps the planets in our solar system in orbit around the Sun.
  2. Misconception: The moon orbits Earth because Earth’s gravity pulls on it, but the moon doesn’t have gravity.

    • Clarification: The moon does have gravity, albeit weaker than Earth’s. This gravitational force is what causes tides on Earth. Both Earth and the moon exert gravitational forces on each other.
  3. Misconception: Gravity is the only force acting on planets in the solar system.

    • Clarification: While gravity plays a dominant role in celestial mechanics, other forces like electromagnetic forces are also present. However, on the scale of planets and galaxies, gravity is the most influential.
  4. Misconception: The sun doesn’t move; everything in our galaxy revolves around it.

    • Clarification: The sun orbits the center of the Milky Way galaxy. The center of our galaxy has a supermassive black hole, and the gravitational forces at play cause everything, including the sun, to orbit around it.
  5. Misconception: Black holes wander the universe, “sucking” everything in their path.

    • Clarification: Black holes don’t move around like cosmic vacuum cleaners. They exert gravitational forces like other celestial objects. It’s only when objects come extremely close to them that they might be “pulled in.”
  6. Misconception: Gravity acts instantaneously over vast distances.

    • Clarification: Changes in gravitational forces, such as those caused by an object moving, propagate at the speed of light. It’s not an instantaneous effect.
  7. Misconception: Heavier objects exert more gravity.

    • Clarification: While mass is a factor in gravitational force, distance also plays a significant role. A smaller object close by can exert a stronger gravitational pull than a more massive object that’s farther away.
  8. Misconception: Stars don’t exert gravitational forces; only planets and moons do.

    • Clarification: Every object with mass, including stars, planets, moons, and even you, exert a gravitational force. It’s just that on a cosmic scale, only the more massive objects’ gravitational forces have noticeable effects on other celestial bodies.
  9. Misconception: Comets and asteroids in our solar system move randomly.

    • Clarification: The motions of comets and asteroids are also influenced by the gravitational forces exerted by the sun and planets. Their orbits might seem more eccentric than planets, but they are not random.
  10. Misconception: Outer planets, being farther from the sun, should move more slowly because gravity is weaker.

  • Clarification: While it’s true that gravitational force decreases with distance, the outer planets are also more massive and have their own gravitational intricacies. Their speeds are a balance between their inertia and the gravitational pull of the sun.

Scale of Objects in the Solar System

Use the arrows located at the bottom of the presentation to navigate through all the bell ringer questions.

  1. Misconception: All planets are roughly the same size.
      • Clarification: Planets in our solar system vary widely in size. For instance, Jupiter is the largest planet, with a diameter over 11 times that of Earth, while Mercury is just slightly larger than our Moon.
    1. Misconception: Pictures of celestial bodies, like those in textbooks or online, are to scale.

      • Clarification: Often, images of celestial bodies are not to scale to make them more visible or understandable in the context. Actual size comparisons might be quite different than perceived from such illustrations.
    2. Misconception: All planets are equally distant from each other.

      • Clarification: The distances between planets in our solar system are not uniform. For example, the distance from Mars to Jupiter is much greater than the distance from Earth to Mars.
    3. Misconception: Surface features, like volcanoes and canyons, are roughly the same size across different planets.

      • Clarification: Surface features can vary drastically in size across different celestial bodies. For instance, Olympus Mons on Mars is the largest volcano in the solar system, much larger than any on Earth.
    4. Misconception: The rings around a planet are solid structures.

      • Clarification: Rings, like those around Saturn, are made up of countless small particles, ranging from tiny dust grains to boulders. They aren’t solid discs.
    5. Misconception: When a celestial body looks bright from Earth, it must be large.

      • Clarification: Brightness can be a result of reflectivity, proximity to Earth, or inherent luminosity, not just size. For instance, Venus is very bright from Earth, partly due to its highly reflective clouds, not just because of its size.
    6. Misconception: The moons of other planets are similar in size to Earth’s Moon.

      • Clarification: Moons in our solar system vary widely in size. While some, like Ganymede (Jupiter’s moon), are larger than Mercury, others are just a few kilometers across.
    7. Misconception: Celestial bodies without atmospheres must be small.

      • Clarification: Size and the presence of an atmosphere are not directly correlated. For example, Mercury is larger than our Moon but has a much thinner atmosphere.
    8. Misconception: All data about celestial bodies are collected using telescopes.

      • Clarification: Data can be collected using various instruments, including space probes, landers, and orbiters, not just telescopes.
    9. Misconception: Space-based telescopes always provide clearer images than Earth-based ones because they’re closer to the objects being observed.