Early Astronomers Contributions

Contributions of Early Astronomers

• Nicolaus Copernicus (1540) studied planetary movements and stars
• Copernicus determined Earth rotates on its axis, causing day and night
• Copernicus proposed the Sun is at the center, with planets moving around it
• Johannes Kepler (1571) stated planets move in ellipses
• Galileo Galilei (1609) used the telescope effectively and discovered:
  • Mountains on the moon
  • Phases of Venus
  • Moons of Jupiter
• Galileo Galilei observed the Sun's rotation by following sunspots
• Galileo Galilei was forced to recant his findings
• Sir Isaac Newton (1665) formulated the law of gravitation
  • Bodies attract each other, force proportional to masses and inversely proportional to distance
• Newton determined the moon causes tides
• Newton discovered prisms separate light, spectral analysis of stars
• William Herschel (1781) discovered Uranus and the existence of double stars -Herschel determined the general shape of the Milky Way
• Albert Einstein (1919) developed the theory of relativity Motion, time, and distance are relative
• Einstein explained the universe with curved space-time
• Edwin Hubble (1950s) found galaxies moving away, indicating an expanding cosmos
• Stephen Hawking (2000s) proposed the universe had a beginning and will have an end
• Vera Rubin (1970s) proved the existence of dark matter
  • Rubin studied the motion of stars in the Andromeda galaxy

The Big Bang Theory

• The Big Bang Theory is a scientific explanation for the beginning of the universe
• Cosmic background radiation is evidence supporting the Big Bang Theory

Age of the Universe

• Scientists estimate the universe's age using Edwin Hubble's theory of expansion
• The estimated age of the universe is 13.7 billion years old

Possible Outcomes for the Universe

• Open Universe: Expansion will never stop
• Closed Universe: Expansion stops and turns to contraction
• Flat Universe: Expansion slows to a halt infinitely but never contracts

Dark Matter

• Dark matter consists of subatomic particles not yet found
• Fred Zwicky observed galaxies in the Coma Cluster moving faster than their escape velocity which provided evidence for dark matter

Large Hadron Collider (LHC)

• The LHC is the most powerful particle accelerator
• It has possibly discovered hints of new physics

Variable Stars

• Variable stars pulsate in brightness due to expansion and contraction of outer layers
• They help determine distances to cluster stars

RR Lyrae Variables

• These stars have pulsation periods between 1.5 hours and 1 day
• They possess the same luminosity on average

Cepheid Variables

• These stars have pulsation periods between 1 and 100 days
• Their luminosity doubles from dimmest to brightest

Galaxy Centers

• Supermassive black holes occupy the center of most galaxies
• Sagittarius A* is at the Milky Way's center and is a supermassive black hole
  • It has 2.6 million times the Sun's mass but is smaller than our solar system

Galaxy Classifications

• Disk-like galaxies include spiral galaxies, barred spiral galaxies, and flat disks
• Elliptical galaxies are not flattened and lack spiral arms
• Irregular galaxies do not have a distinct shape

Our Galaxy

• We belong to a disk-like galaxy, specifically a barred spiral galaxy

Active Galactic Nucleus (AGN)

• AGN is the core of an active galaxy with highly energetic objects
• Quasars are examples of extra-bright AGNs that are very luminous and distant

Dark Nebula

• A dense cloud of gas and dust that blocks light

Protostar

• The earliest stage of star formation before nuclear fusion which forms from a collapsing cloud of gas and dust

Main Sequence Star

• A star in its longest, most stable phase that generates energy by fusing hydrogen into helium

Supergiant/Red Giant

• Stages in a star's life cycle after hydrogen fuel is exhausted

White Dwarf

• The remnant core of a red giant after shedding its outer layers

Black Dwarf

• A cold, dark, dead remnant of a white dwarf

Supernova

• A massive explosion when a star reaches the end of its life cycle

Neutron Star/Pulsar

• A remnant core of a massive star after a supernova

Black Hole

• A region where gravity is so intense that nothing can escape

Star Death

• A star's mass dictates its life cycle and how it will die

Types of Spectra

• Continuous Spectrum: Light with no breaks
• Emission Spectrum: Contains bright lines from emitted wavelengths
• Absorption Spectrum: Shows dark bands from light passing through a substance

Parallax

• Parallax is the apparent shift in position due to the observer's motion
• Closer stars have a larger parallax shift, measured by angle

Magnitude

• Apparent magnitude refers to how bright a star appears
• Absolute magnitude refers to how bright a star would appear at a distance of 10 parsecs
• Luminosity is the energy output from a star's surface per second

Telescopes

• Kepler searches for Earth-like exoplanets
• Hubble observes distant galaxies, stars, nebulae, and other phenomena
• Spitzer observes the universe in infrared wavelengths
• James Webb observes the early universe, galaxy formation, and exoplanet atmospheres

Telescope Types

• Refracting telescopes use lenses to form images
• Reflecting telescopes use mirrors to form images

NASA Spinoffs

• Satellites: Originally for NASA and military communication
• Smoke Detectors: To detect fire in spacecraft
• Thermal Gloves: For space exploration
• Firefighter equipment: For fighting fires on spacecraft

NASA and CSA

• NASA conducts research and development in space exploration and scientific discovery
• CSA coordinates Canadian space activities, research, and technology

International Space Station (ISS)

• The ISS is a platform for international collaboration and research in space

Space Transportation System (STS)

• STS aimed to provide regular space access for science and human spaceflight to deploy satelites

Future NASA Missions

• Moon to Mars Project: Study human response in deep space
• Testing tools, instruments, and equipment for future Mars missions on the moon
• Lunar Gateway Project: Sustaining human space exploration goals
  • CSA contribution is the Canadarm 3, lunar surface access, and Mars missions

Current NASA Mission

• The James Webb Space Telescope observes distant galaxies, exoplanets, and the early universe