SE1: Ancient Knowledge & Understanding Space

SE1.1: What do we understand about celestial bodies?

• Ancient People:

  • Watched the motion of celestial bodies

  • Believed stars revolved around the Earth

  • Observed patterns and cycles

  • Used this knowledge to predict seasons, and create myths

• Constellations:

  • Many ancient cultures recognized and named constellations (groups of stars)

    • Ursa Major is well known in most world cultures and associated with a number of myths

  • The position of constellations appears to change with the seasons. This is due to the Earth’s rotation and orbit around the Sun.

• Sky Coordinates: Early astronomy concentrated on finding accurate positions of the stars and planets. There are a couple of popular ways of specifying the location of a celestial object.

  • Equatorial Coordinates (Longitude and Latitude)

  • Altitude and Azimuth

SE1.2: How have views of our solar system changed?

• Aristotle: Proposed Geocentric Model of the Universe

• Ptolemy: Attempted to explain retrograde motion (Actual or apparent motion of a body in a direction opposite to that of other bodies in its system) by including small epicycles

• Copernicus: Proposed Heliocentric Model of the Universe

• Hans Lippershey: Invented the telescope in 1608

• Galileo Galilei: Improved the telescope and contributed to the Heliocentric Model

  • Observed that the moon has mountains and craters on it, which had shadows depending on the Sun’s angle on them

  • The Sun rotates on its own axis

  • Jupiter is accompanied by four small moons

  • Stars are much farther away than the planets

• Johannes Kepler: Predicted that the planets moved in elliptical orbits rather than circular orbits, explained retrograde motion

• Newton: Law of Universal Gravitation states that any two bodies in the universe attract each other, which provides an explanation for Kepler’s idea of elliptical orbits

• Jansky/Reber: Invented Radio Telescopes in 1930s

SE1.3: How have telescopes been used to increase our understanding of space?

• Types of Telescopes

  • Refracting: Have objective and eyepiece lenses

    • Good for planetary viewing

    • Expensive

  • Reflecting: Have objective mirrors and an eyepiece lens

    • Good for deep sky viewing

    • Cheaper

  • Combination: Have an eyepiece lens and objective mirrors

    • Best overall design

    • Excellent for planetary and deep sky viewing

    • Expensive

  • Radio

    • Invented by Jansky/Reber in the 1930s

      • Can penetrate dust clouds

      • Computers false colour the radio wave data to product images

      • Lower resolving power than optical telescopes

      • Can be used day and night

• Magnification: (Refracting telescope)

  • Focal length of OBJECTIVE LENS/Focal length of the EYEPIECE LENS

• Resolving Power: Determines the fineness of detail a telescope can product of an object in view

• Interferometry: A technology that connects 2 or more telescopes to combine their images

• Adaptive Optics: A technology for ground based telescope that adjusts the mirrors of a telescope or the image they product to cancel the effects of atmospheric distortion

• Ground Based Telescope:

  • Often built in elevated locations

  • Cheaper

  • Easier to maintain

• Space Telescope:

  • Can view distant planets, galaxies, and astronomical objects

  • Clearer images (Outside of Earths’s atmosphere)

  • Expensive

  • Difficult to maintain

  • Hubble (1990)

  • James Webb Telescope (2021)

SE1.4: How can you determine the composition of a star using spectroscopy?

• Life cycle of a star

  

• Isaac Newton (1672):

  • Refracts white light with a prism, resolving it into its components (ROYGBIV)

  • Passed light through 2 prisms to prove that light was made up of colours rather than prisms being responsible for colouring the light

• Spectroscopes:

  • A scientific instrument that splits light into its different wavelengths, which humans see as different colours

  • Originally used prisms, but now use a series of closely spaced slits called a diffraction grating

  • First invented by Joseph von Fraunhofer in 1814 to observe the sun’s spectrum, observed dark lines in the sun’s spectrum (spectral lines)

SE2: Modern Technologies & Space Exploration

SE2.1: What other techniques are used to determine more accurate information about celestial bodies?

• Triangulation

  • A very old method to indirectly measure the distance to an object

  • Used in surveying, navigation, astronomy, rocketry, and weaponry

• Triangulation Method

  • Step 1: Create and measure a baseline

  • Step 2: Measure the angles from the ends of the baseline to the distant object

  • Step 3: Create a scale drawing from your measurements

  • Step 4: Using your drawing, measure the shortest distance from the baseline to the object

  • Step 5: Convert that distance from scale to real units\

• Parallax

  • Astronomers estimate the distance of nearby objects in space by using a method called staller PARALLAX

  • They measure a star’s apparent movement against the background of more distant stars as Earth revolves around the sun

  • Parallax is similar to using triangulation to locate a nearby object on Earth

  • Measurements are made 6 months apart which creates a very long baseline