Week 5: Galaxies to Black Holes

 1. What did you do in lab today? 

Meteors, meteorites, Craters, and Comets

• Meteor --> a small body of matter from outer space that enters the earth's atmosphere
• meteorite --> part of it strikes the grounds, not actually a shooting star
• Craters --> circular shape on surface commonly formed by meteors
• Comets --> icy rocky celestial body composed of frozen gases, dust, and organic compounds
• Meteors: space rocks that burn in earth's atmosphere 
• if a meteor makes it though the atmosphere and lands on Earth, its a meteorite
• 3 kinds: irons, stones, and stony-irons
• Craters: earth has about 190 craters 
• largest impact crater on earth is the Vredefort located in South Africa --> 180 - 300 km wide
• Manson Crater --> in Iowa 22 miles in diameter 

Galaxies

• galaxies are made up of stars only 
• galaxies and solar systems are the same thing
• the milky way is the only galaxy
• the sun is the center of the milky way
• galaxies are made up of planets, stars, and lots of gas and dust held together by gravity 
• most have black holes 
• oldest galaxy was formed 500 billion years ago 
• there are 50 galaxies surrounding us and they are called the "local group"
• clusters could have up to 1000 galaxies 
• scientists are still debating which came first: galaxies or black holes 
• galaxies can collide and merge: milky way and andromeda in 4.5 billion years 
• large galaxies can cannibalize smaller ones 

Black Holes

• black holes suck everything in
• all black holes are gigantic
• black holes lead to another universe
• black holes are not actually holes 
• huge clusters of matter that are packed into very small spaces
• very dense 
• different types of black holes, stellar, supermassive, primordial
• previously called dark stars 
• Albert Einstein presented a theory that is now the basis for black hole studies
• nothing can escape it, even light 
• milky way black hole is called Sagittarius A* (ey-star)
• 4 million times the sun's mass
• closest known black hole is about 1,500 light-years away

2. What was the big question? How did the universe, our solar system, and the life on Earth come to be? What processes continue to shape them? 

3. What did you learn in Thursday's discussion? 

Notes:

• northern hemisphere turns clock-wise
• southern hemisphere turns counter clock-wise
• on equator no spin 

Life Cycles of Stars

• stellar nebula --> bunch of gas 
• when our sun "turned on" it likely blew all the gases off the inner 4 planets 
• sun was born out of bunch of gases
• sun is held together from mass
• as it burns fuel its mass decreases, its gravity also decreases, it begins to inflate (Red giant)
• Our star (SUN) formed from a stellar nebular most likely from a star that underwent a supernova
• nuclear fusion - stars can make up to IRON (Fe) on the periodic table of elements
• sun is about halfway through its sequence 
• when a star goes supernova (explodes) it builds the rest of the periodic table 

Asteroid Belt

• belt itself resides between Jupiter and Mars 
• many theories as to what the belt is from, exploded planet, tried to become planet but not enough mass 
• out of the belt theres chunks of rocks, meteoroids, comets
• Comet: icy body that releases gases as it orbits the sun
• Meteoroid: rocky or metallic fragment of an asteroid, comet, or planet
• Meteorite: meteor fragment that reaches the ground
• If it hits the earth it leaves a crater 
• Asteroid: rocky body smaller than a planet that orbits the sun
• Meteor: streak of light seen when a meteoroid heats up in the atmosphere

Galaxies 

• We live in the milky way - specifically on Orion's arm, in a spiral galaxy
• three primary shapes: spiral (pinwheel), elliptical (Circular), irregular (everything else)
• Each galaxy contains approximately 200 billion stars 
• there are over 2 trillion galaxies
• super massive black hole in the center of most galaxies - provides the gravitational pull that holds it all together 
• If we go to our nearest star (Alpha Centari) it would take 81,000 years

Black Holes 

• Super dense 
• nothing, including light, can escape
• center of galaxies 

Inner Planets

• Mercury, Venus, Earth, Mars
• terrestrial/rocky
• three moons total (Earth has 1, Mars has 2)

Outer Planets

• Jupiter, Saturn, Uranus, Neptune
• Gas/Ice (methane not H20)
• 143 known moons
• many rings

Plane of the ecliptic: Pluto kicked out (clear area, plane)

4. Read online textbook, chapter 5:

- What did you learn? 

• Stars form through nebulae though gravitational attraction and nuclear fusion, their life cycles vary based on mass
• Our solar system formed 4.65 billion years ago from a rotating nebular, with the sun containing 99.8% of its mass
• Galaxies are vast systems held together by gravity, often centered around black holes 
• Black holes are formed from supernovae and have immense gravity that traps light, the first image of one was captured in 2019.

- What was most helpful? 

• The life cycle of stars and how their mass determines their fate
• The origin story of the moon and its impact on Earth's tides
• the historical timeline of space exploration, especially the inclusion of women's contributions

- What do you need more information on?

• How nuclear fusion progresses to form elements beyond iron
• the mechanics and current research on black holes and their role in galaxy formation
• more detail on the role of dark matter and dark energy in the universe's expansion

5. What questions, concerns, and/or comments do you have? Could someone ever exit our galaxy? How long would it take? If not, how do they know there's other galaxies if we could never leave?