Astro 4

The Universe is approximately 13.8 billion years old, and the Solar System is about 4.6 billion years old.

Earth < Solar System < Milky Way < Local Group < Superclusters < Observable Universe, with each category being vastly larger than the previous.

Age of the universe: ~13.8 billion years; Solar system: ~4.6 billion years; Human history: ~200,000 years; Average human life: ~70-80 years.

Information can only travel at the speed of light, so we observe Alpha Centauri as it was 4.37 years ago.

It would take 10 minutes for the signal to reach Mars and 10 minutes to return, so the total wait time is 20 minutes.

Gravitational force increases with mass and decreases with the square of the distance between the objects.

Acceleration due to Gravity would increase fourfold (gravity ∝ 1adius²).

Newton used the Moon and its orbit around Earth.

It would lose altitude and eventually fall toward Earth due to reduced centripetal force.

Cavendish used a torsion balance to measure gravitational attraction between masses, allowing him to calculate Earth's mass.

They were looking for the "aether," a hypothetical medium for light waves.

The speed of light is always measured as ~300,000,000 m/s, regardless of the source's motion.

The speed of light is constant in all inertial frames, and the laws of physics are the same in all inertial frames.

They would disagree on time intervals, lengths, and mass.

The object's mass increases as its speed approaches the speed of light.

Moving objects appear shorter along the direction of motion to an outside observer.

A moving clock appears to run slower relative to a stationary observer's clock.

One twin travels at high speed and ages more slowly than the twin who remains stationary, due to time dilation.

The gamma factor (γ) approaches infinity as the object's speed approaches the speed of light.

Energy (E) and mass (m).

Rest mass is the mass of an object at rest, and rest energy is the energy due to this mass, given by E=mc².

The equivalence principle, stating that gravitational and inertial forces are indistinguishable in small regions.

Space-time is a combined four-dimensional framework of space and time, influenced by mass and energy.

Objects moving under no external force in a straight line, such as freely falling objects.

On Earth's surface, we are not inertial observers due to experiencing the normal (upward) force from the ground.

Clocks run slower, and lengths contract as gravitational strength increases.

Light from stars bent around the Sun, showing gravitational effects on light, which Newton’s laws didn’t account for.

An object in orbit follows a curved path in space-time due to the curvature caused by a massive body.

Mercury's orbit, specifically the precession of its perihelion, was better explained by general relativity.

Photon energy increases as wavelength decreases.

Wavelength and frequency are inversely related.

Gamma rays and X-rays have the highest photon energies.

Electrons orbit the nucleus in fixed energy levels and emit/absorb energy when changing levels.

Emission lines are created when electrons drop to lower energy levels, releasing photons.

By analyzing its unique emission or absorption spectrum.

Dense materials like solids and liquids emit a continuous spectrum.

Higher temperatures shift peak wavelength to shorter, bluer colors.

Mercury’s orbit.

Energy required to separate components of a molecule, planet, or nucleus.

Chemical and gravitational energy; ruled out because they couldn't sustain the sun’s output over billions of years.

The gold foil experiment showed most alpha particles passed through, implying a small, dense nucleus.

It suggested a dense, positively charged nucleus, contrary to the "plum pudding" model.

The electron.

It’s about 100,000 times smaller than the atom.

Nuclear forces are much stronger than external conditions.

Protons and neutrons; protons are charged, neutrons are neutral.

Variants of an element with the same protons but different neutrons.

Nuclei consist of protons and neutrons, held by nuclear forces, and can release energy.

Nuclear bonds release millions of times more energy.

Hydrogen nuclei fuse to form helium, releasing energy.

It’s slightly less due to energy released in fusion.

Yes, through neutrinos and sunlight.

The balance between gravity pulling inward and pressure pushing outward.

By studying solar system materials and modeling stellar evolution.

Roughly halfway through its main sequence phase.

Gravity and light intensity diminish with the square of the distance.

Brightness depends on luminosity and distance.

Parallax is the apparent shift in a star's position; larger angles mean closer distances.

Stars range from 0.1 to over 100 solar masses, with luminosities varying greatly.

Higher mass increases luminosity but shortens lifespan.

Massive, blue stars.

From the color and spectral type of the star.

Red dwarfs are most common; massive blue stars are rare.

In the innermost core, where temperatures and pressures are highest.

It gradually increases as the core temperature rises.

Hydrogen is depleted; helium fusion begins, producing heavier elements.

Helium nuclei fuse to form carbon in the core of aging stars.

A white dwarf.

Medium-mass stars become planetary nebulae; massive stars become supernovae.

About 90% of its life.

Because larger nuclei have more repulsive forces and fewer binding interactions.

Formed in supernova explosions and through processes in massive stars.

Fusion combines light nuclei to form heavier ones; fission splits heavy nuclei into lighter ones.

Iron; it has the largest binding energy per nucleon.

They have more stable configurations and more ways to pair nucleons.

Iron fusion absorbs energy instead of releasing it, leading to collapse.

Low to medium mass stars become white dwarfs; massive stars become neutron stars or black holes.

Its radius decreases as it gains mass due to increased gravitational pressure.

The maximum mass (about 1.4 solar masses) a white dwarf can have before collapsing into a neutron star.

Electron degeneracy pressure stops white dwarf contraction; neutron degeneracy pressure stops neutron star contraction.

A nova is a sudden brightness increase in a binary system; a supernova is a massive explosion of a star.

Type Ia occurs in binary systems with white dwarfs; core collapse happens in massive stars.

White dwarfs are about the size of Earth; neutron stars are about the size of a city.

A rotating neutron star emitting beams of radiation.

The boundary beyond which nothing can escape the black hole's gravity.

A fundamental force that obeys the inverse square law

A small clustering if galaxies that includes the milky way

A packet of light energy

An idealized object that absorbs all incoming radiation and outputs a spectrum based on its thermal equilibrium

A model of the atom where negatively charged electrons orbit a positively charged nucleus

What we see in a spectrum when an electron drops down an energy level

Chemical composition

A strong and attractive force but it is short ranged

.08 solar masses

What is a white dwarf

an object will not change its motion unless a force acts on it. the force on an object is equal to its mass times its acceleration. when two objects interact, they apply forces to each other of equal magnitude and opposite direction