Topic 3.1 - Constellations

• Point of light in the sky
• Vary in size, temp and therefore colour
• Twinkle close to horizon due to turbulent air

• 2 or more stars gravitationally linked
• In the same area of space
• Can be viewed through telescope
• Light output as one eclipses the other
• Doppler shift in spectra

• Appear next to each other
• Millions of kms apart
• e.g. Alcor and Mizar in the Plough

• Group of stars that appears to make a pattern in the sky
• Look close but usually far apart
• May not be gravitationally linked
• Pattern line of sight effect
• See different constellations at different times of year
  • Due to Earth's rotation and tilt of axis
• Appearance may be altered when planet passes in front
• Official area of sky containing a pattern of stars

• Pattern of stars
• May (not) be linked to constellation
• e.g. the Plough, Summer/Winter triangle
• Fun/popular name for a pattern of stars

• Group of stars close to each other in space
• Bright and relatively young
• Group of a dozen - 1000 stars
• Found around galactic plane
• e.g. Pleiades

• Faint, fuzzy appearance
  
• Blueish in colour
• A few bright stars visible
• Patch of many stars

When stating 2 facts, state age & number

• Spherical shaped group of stars
• Dimmer and older
• Found around galactic nucleus/halo/bulge
• Usually old red giants/white dwarfs packed tightly
• 100,000-1,000,000 stars
• e.g. M13 in hercules

When stating 2 facts, state age & number

• Blurry patch of light in space
• Where stars are born/dying/have died
• Not necessarily galaxy, can be an object in our galaxy

• Labelled with Greek alphabet
• Bayer designation
•  α, β, γ, ẟ, ε
• Doesn't take into account variable brightness
• Sometimes alpha isn't brightest
• Constellation boundaries have changed

• Original losts in 2000BC by early Babylonian farmers
• Used stars for calendars and navigation
• Compendium of constellations: 'The Almagest' by Ptolemy
• Many based on Greek mythology
• Constellations added when southern hemisphere explored
• List formalised by IAU in 1920s to 88
• Chinese/Indian/Aboriginal had own (names for) constellations