Astronomy 101

Alexa Fogarty

Astronomy 101

• Astronomy is the study of the Universe and all its phenomena using math, chemistry and physics
• This powerpoint covers life cycles of celestial objects, how they were discovered, and their evolution including:
• Evolution of galaxies
• Formation of planets andtheir characteristics
• Life cycles of celestial objects: Example Stars

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The Universe

• The universe and all that is in it, is a complex system similar to those on Earth
• The Universe though is hypothesized to be around 14 billion years old and containing substances that are beyond human comprehension
• Astronomers speculate that the Milky Way (our galaxy) started to form 4.6 billion years from just a spinning cloud of dust and gas
• Just like humans and plants, stars and cosmic objects have life cycles, although the entire cycle is not observable by an individual human since they can last millennia or more

Evolution of Galaxies

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Galaxies

• In the universe, there are billions of galaxies, most of which are unobservable by people in the Milky Way
• Astronomers hypothecate that galaxies form from dust and gas clouds collapsing in on themselves by their own vigorous gravitational pull which allows stars to form and create different types of galaxies
• Light from stars in these galaxies travel all the way to the Milky Way in a process called Red Shift, which is the astronomical version of the Doppler Effect
• We can now take high definition photos of these galaxies and other celestial objects thanks to the ground breaking technology of the Hubble telescope

The Doppler Effect

• The Doppler Effect is the change in wave frequency in relation to its observer, so as it gets closer the pitch gets higher and as it recedes it gets lower
• For example, when you hear a siren from far off and it comes closer until it's blaring in your ear then slowly fades away as it leaves you behind, is what humans call the Doppler Effect

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(Quora)

• Redshift is the astronomical version of this. As a galaxy moves away from us, the light from its stars gets fainter

The 3 major types of galaxies are:

1. Elliptical
2. Spiral
3. Irregular

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(Futurism)

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Formation of Planets and their Characteristics

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Density, Mass, and Volume

• Density, Mass and Volume play important cosmic roles in astronomy
• Density: helps determine what a planet is made up of also known as the degree of compactness of a substance
• Mass: helps define large matters in space also known as the property of a physical body
• Volume: helps determine size of planets also known as the quantity of a 3-dimensional space enclosed by a surface
• These metrics help astronomers distinguish planets

(ScienceStruck)

(www.cimt.org.uk)

The Milky Way

• The theory of the Milky Way evolution postulates that a vast cloud of dust and gas spun around the early Sun and it let out a burst of energy, blasting the dust away
• Asteroids, the oldest space rock, started colliding into each other, creating hundreds of protoplanets

(Science Photo Library)

Asteroids

• Asteroids are ancient space rubble that orbit around the Sun mostly between Mars and Jupiter in the Asteroid belt
• Though they may orbit the Sun like planets they are airless, rocky formations that are much smaller than planets
• On many planets, including Earth, you can see craters from where asteroids crashed

• Asteroids are also credited to the creation of planets
• In the early days of the Milky Way, asteroids were pulled together by gravity and coalesced to make the protoplanets
• Millions are still in space today and their irregular shapes are visible today through telescopes and pictures

The Early Planets

• The early planets, protoplanets, were formed by asteroids colliding, and as the masses got larger the pull of gravity got more intense
• Protoplanets eventually became the 8 major planets we know today, Mercury, Venus, Earth, Mars, Jupiter, Saturn Uranus, Neptune
• The protoplanets get transformed, by colliding into one another repeatedly and eventually started to just orbit the sun and evolving into the terrestrial and gas planets in our solar system
• For more information:

https://ny.pbslearningmedia.org/resource/flbe12.sci.ess.eiu.planetform/how-the-inner-solar-system-formed/support-materials/

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The 8 Major planets

• The 8 major planets now seen today took millions of years to evolve
• The 4 inner, terrestrial planets (Mercury, Venus, Earth and Mars) have liquid inner cores and solid out cores; they are closest to the sun
• The outer gas giants(Jupiter, Saturn, Uranus, and Neptune) have cores of rock and ice with varying elements surrounding it including hydrogen, methane gas, and helium

(Google Sites)

Scale

• Each planet has a gravitational pull, so things have different weight on each planet
• Though an object may keep the same mass, its weight may differ since weight is the amount of gravity it takes to keep something grounded
• Example:

Elements

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• All planets are made of different elements and the elements help astronomers interpret the galaxy
• The simplest and most common element is Hydrogen followed by helium (both are essential to the makeup of the Universe)
• We breathe common elements known as Oxygen, but we also inhale other gases such as nitrogen, argon, neon, helium, and hydrogen
• Gases saturate the atmosphere of many planets and other celestial objects
• The Sun is made up of elements such as Hydrogen, Helium, Oxygen, and Carbon

Earth

• Earth is the only astronomical object found to harbor life in the Milky Way and is one of the terrestrial planets with a solid and hot inner core
• A terrestrial planet is one that is made mostly of metals and silicate rocks

• Earth was first thought to be the central object in the solar system but that theory was later corrected by Polish astronomer, Copernicus asserting the sun was the center
• Earth was formed about 4.5 billion years ago and evolution of life can be traced to about 3.5 billion years ago from fossils found

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Fun Fact: Earth is the only planet with liquid water on the surface

Earth

• Our solar system has many moons, but Earth only has one
• Earth’s moon is supposedly formed from molten rock ricocheted back into space when protoplanets collide and coalesce in space
• The moon turned out to be 1/4 the size of Earth
• As the moon orbits the earth it goes through stages that are visible to people on Earth

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(TimeandDate.Com)

Dwarf Planets

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• Dwarf Planets are cosmic objects that resemble small planets but don’t meet the criteria to be classified as a planet
• The current dwarf planets are:
• Pluto 4. Makemake
• Ceres 5. Haumea
• Eris
• Except for Eris, which is in the main asteroid belt, the rest are in the Kuiper Belt, a region that contains more space residue

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(Slideplayer)

Pluto

• Pluto is a planet of frozen plains and ice mountains with red snow
• Pluto is perhaps the most well-known dwarf planet since its being downgraded from an actual planet in 2006 by the International Astronomical Union (IAU)
• Pluto was the first object to be found in the Kuiper Belt and is also the largest
• It was found in 1930 and was considered the ninth major planet for 76 years until it was declared that it didn’t meet all the criteria
• This caused global rage and many protested against, trying to sway the IAU’s decision but it is still considered a dwarf planet today since it doesn’t “clear the neighborhood”
• “Clearing the neighborhood” refers to a planet being the largest force of gravity and having no other bodies comparable to its size nearby except its natural satellites

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Life cycles of Celestial Objects: Example Stars

Life Cycles

• The life cycle of astronomical entities is similar to those found in naturally occurring objects on Earth
• Example: Stars
• Stars are born when dust and gas clouds fuse together and they slowly get brighter as they age
• The average star lives about 10 billion years and their light can be seen from Earth
• When a star goes supernova it gets increasingly bright and exerts more energy in seconds than the sun in its lifetime
• Stars at the end of their life collapse to form red giants and dense white dwarfs

(National Schools’ Observatory)

Fun Fact:The light from stars in other galaxies takes years to reach us, hence the phrase “light-years”

Summary

• The creation and evolution of our Universe and the galaxies took many millennia to establish and are still, billions of years later, evolving and expanding
• The origin of Earth and other celestial objects was dust and gas yet they evolved with unique characteristics
• The circle of life in galaxies is not as different then some might think compared to ours and our understanding will only be augmented by time
• Astronomers are continually learning and refining our understanding of the cosmos