Big Bang Story Continued .....

Big Bang Story Continued .....

Krystal Cabrera

​Phase 4: Stars, Galaxies, and Supernovas

​Era of stars

As early as 200 million years old, the first stars formed. The early universe was mainly hydrogen and helium. If you look at our sun, it consists of mainly these two elements. They form from large clouds of dust and gas which collapse and break down. Sir Isaac Newton states that the force of gravity pulls into a core. As time goes on, the expanding cloud of hydrogen gas bundles together to build stars. These stars start rotating and become part of our Milky Way galaxy.

​Phase 4: Stars, Galaxies, and Supernovas

​Era of galaxies

After 1 billion years, galaxies finally form. Stars are the building blocks for galaxies. As more stars bundle together, we have stars attracting other ones. This forms new galaxies, which are just groups of stars. Most stars are at the center of the galaxy with few at outer edges. Galaxies tend to flatten out as they rotate. Even the Earth is longer on the rotational axis due to its rotation. We classify galaxies using the Hubble Galaxy Classification scheme. For example, there are spiral, elliptical, and irregularly shaped galaxies

​Phase 4: Stars, Galaxies, and Supernovas

Dying stars and supernovas

Stars are massive balls of burning gas emitting light and heat. Over millions of years, stars can run out of fuel and burn out. But there are some types of stars that turn into supernovas. Supernovas collapse in a matter of seconds and release a tremendous amount of energy. After they explode, it’s so massive that the energy can be seen right across the galaxy. These explosions are like factories building heavier elements such as uranium and gold. Whereas from a dying red dwarf and larger, we obtain elements ranging from carbon, oxygen, and iron. The first supernova is estimated at 10.5 billion years ago. Pieces of these exploding stars have been incorporated into our planet and even our bodies.

Multiple Choice

Elliptical, spiral, and irregular are all types of ______.

• solar systems
• universes
• galaxies
• stars

Multiple Choice

A  _________________________ is a sphere of very hot, burning gas.

• star
• galaxy
• moon

​Our solar system

If you want to build a planet, you’re going to need a star. Dying stars are atom factories because they make carbon, iron, and nickel when they are fully exhausted. All this matter is pulled together by gravity. For Earth to exist, there must’ve been a star that died. If you look deep inside Earth, its core is mostly iron and nickel. And these elements could have only come from the death of a star. It could have even incorporated matter from other supernovae. If you slice any planet, it has layers. Whereas protoplanets are homogenous. Outwards from the star, they become less dense and made of frozen ices. For example, our solar system has 9 known planets. Mercury, Venus, Earth, and Mars are most dense. We live in one of the spiral arms of the Milky Way.

​Phase 5: The Story About Us

​​Phase 5: The Story About Us

​Supernova is in our blood

If you look at the human body, 60% is hydrogen and oxygen. Hydrogen has been around since the Big Bang. So that means that most of the atoms in your body came from the Big Bang. That would put you at about 13.7 billion years old. If you take a closer look at the blood circulating in your body, it has elements like magnesium and iron. These were built from the dying stage of a star or supernovas. So that means that your body is made of remnants of exploding supernova. So we wouldn’t exist if it wasn’t for

​​​Phase 5: The Story About Us

​Some stars you see don’t exist anymore

Light is the fastest thing we know moving at a speed of 300,000 km/s. Despite traveling at the speed of light, it takes 8 minutes and 20 seconds for sunlight to reach us. Note, imagine a star further away. For some stars in the night sky, you’re seeing light that has traveled millions or billions of years to reach us. Just like us, stars have life spans. So the star that emitted the light may not even exist at the time you see it. For stars that are visible to the human eye, chances are they still exist. But for galaxies millions or billions of light-years away, they’re long gone.

Multiple Choice

The distance light can travel in one year is ______________

• 15,000 kilometers

• 1 light-year

• 15 Astronomical Units

• 6,000 miles

Multiple Choice

A light year is a measurement of

• time

• distance

• speed

• velocity

​The Big Bang Time Line

The first seconds

• 13.7 billion years ago: Big Bang

• At 10^-34 seconds: Universe undergoes rapid inflationary expansion. Because the universe expanded at faster the speed of light, the light from those parts of the universe can never catch up to us. At this point, there was only intense energy and no particles.

• At 10^-32 seconds: First subatomic particles that made matter started forming.

• From 10^-11 seconds: Four forces of the universe are entirely separated.

• At 10^-5 seconds: First protons and neutrons forming. Temperature drops. But it’s still too hot for stable atoms to form.

• At 1 second: First electrons form with the Big Bang now 3-light years in size.

• From 3 minutes: First stable atoms with a nucleus and electrons. Temperature becomes 100K.

​The Big Bang Time Line

​The first stars

• 13.6 billion years ago: First star (Methuselah)

• 13.5 billion years ago: First black hole

• 13.2 billion years ago: First galaxy

• 12.7 billion years ago: Milky Way forms

• 6.8 billion years ago: Milky Way galaxy arms start spiraling

• 6.0 billion years ago: Alpha Centauri forms

• 5.5 billion years ago: Milky Way becomes spiral galaxy

• 4.6 billion years ago: Our sun

• 4.5 billion years ago: Our solar system

• 4.5 billion years ago: Earth forms