Physics of Light and Matter

A red sweater reflects red light and absorbs other colors.

Light is a form of energy that has properties of both waves and particles.

The leaf's bobbing frequency tells us the ripples' frequency in Hertz, which measures cycles per second.

Wavelength and frequency are inversely proportional; if frequency increases wavelength decreases.

Blue light has a shorter wavelength and higher energy than red light.

The atomic number of carbon or any element is the number of protons in its atom's nucleus. Carbon has 6 protons, so its atomic number is 6.

The atomic mass number is the sum of protons and neutrons in an atom's nucleus.

Arrange light from shortest to longest wavelength: gamma rays, X-rays, ultraviolet, visible, infrared, radio.

14C differs from 12C because it has more neutrons in its nucleus.

The atom has 12 neutrons and protons combined in its nucleus.

A photon of light is absorbed by the electron when it jumps from a lower-energy orbital to a higher-energy one in an atom.

A photon of light is emitted when an electron in an atom jumps from a high-energy orbital to a lower one.

A light bulb filament produces a continuous spectrum of light.

Gasses of different elements have distinctive emission and absorption patterns.

X-rays can be detected from an airplane(higher altitude) but not the ground in many cases.

Telescopes can detect infrared, visible, and radio light.

Each element has a unique spectrum of light.

The hottest stars appear white or bluish-white.

By analyzing its spectrum, we can determine what a gas is made of.

When a light source moves away from an observer, its spectrum shifts to longer wavelengths (red).

Larger telescopes collect more light, enabling the observation of fainter or more distant objects.

By analyzing the light from a thermal source, we can determine its temperature and what it is made of.

Mercury is heavily cratered and has essentially no atmosphere.

Venus's high average surface temperature is due to a strong greenhouse effect.

Solar winds are strong streams of charged particles that originate from the Sun's surface due to large temperature differences.

Comets are leftover planetesimals from the outer solar system that didn't form into planets.

Layered sedimentary rock on Mars indicates that the region once contained water bodies, such as lakes.

Radiometric dating suggests that Moon rocks are about 4 billion years old.

Mercury and Earth's Moon show evidence of heavy cratering, indicating they have been heavily bombarded in the past.

Earth and Venus possess substantial atmospheres.

The lithosphere is Earth's relatively rigid outer layer, made of rock that lies above less rigid rock below.

Earth's magnetic field is generated by the circulation of molten metal in the Earth's core.

This law describes the relationship between the orbital period (time it takes for a planet to complete an orbit) and the average distance of a planet from the Sun. It states that the square of the orbital period is proportional to the cube of the average distance from the Sun.

Seafloor crust is thinner, younger, and denser than continental crust. This is primarily due to the composition: seafloor crust is primarily composed of basalt (dark, dense volcanic rock) while continental crust is mostly granite (lighter, less dense).

The inner planets (Mercury, Venus, Earth, Mars) are denser than the outer planets because only dense materials (like metals and rocks) could condense at the hotter, inner region of the solar nebula where they formed.

Venus does not have a global magnetic field like Earth because it has a solid core, unlike Earth's liquid outer core. This liquid core is needed for generating a magnetic field due to the movement of molten metal.

The Sun is not a first generation star because its composition includes elements heavier than hydrogen and helium. These elements could only be formed in the cores of previous stars that went through their life cycles, exploded as supernovas, and dispersed their material into space.

The solar wind is a stream of charged particles (mainly protons and electrons) constantly emitted from the Sun's corona, travelling outward at high speed. It can affect space weather and Earth's magnetic field.

New seafloor crust is formed at mid-ocean ridges. This is represented by Position 2 in the diagram, where molten rock rises from the mantle, cools down, and forms new ocean crust pushing existing plates apart (sea floor spreading).

The movement of tectonic plates on Earth is like a conveyor belt. Plates are constantly being created at mid-ocean ridges (position 2), move along the surface, and eventually are destroyed at subduction zones (position 1).

Jupiter, Saturn, Uranus, and Neptune are the four giant gas planets in our solar system, known as Jovian planets.

All planets in our solar system orbit the Sun in the same direction, with the same counter-clockwise motion.

The asteroid belt, a region packed with asteroids, lies between Mars and Jupiter.

Comets primarily consist of ices and orbit much farther from the Sun than asteroids, which are mostly rocky.

The Kuiper belt, a region of icy objects and dwarf planets, lies beyond Neptune's orbit.

The image shows an interstellar cloud, potentially similar to the solar nebula, where stars and planets form.

The image showcases a protoplanetary disk around another star, providing evidence for planet formation in such disks.

Asteroids are thought to be leftover planetesimals, the building blocks of planets, from the inner solar system.

A red sweater absorbs all colors of light except red, which it reflects back to our eyes, making it appear red.

The number of times a ripple goes up and down in one second is its frequency, measured in Hertz.

Blue light has a shorter wavelength and higher energy than red light.

The atomic number of an element is the number of protons in the nucleus of its atom.

The atomic mass number of an element is the sum of the number of protons and neutrons in its nucleus.

The electromagnetic spectrum, ordered from shortest to longest wavelength, is: gamma rays, x-rays, ultraviolet, visible light, infrared, radio waves.

Hotter objects emit photons with a shorter average wavelength, higher average frequency, and higher average energy.

Both x-rays and radio waves are forms of light (electromagnetic radiation), but x-rays have shorter wavelengths and higher frequencies.

Gamma rays carry the most energy per photon, followed by x-rays, ultraviolet, visible light, and radio waves.

When a thermal source becomes hotter, it emits more energy at all wavelengths. The peak of the spectrum shifts to shorter wavelengths.

The nucleus of a helium atom contains two protons with positive charges and two neutrons with neutral charges.

The frost line marks the boundary in the solar nebula where temperatures are low enough for ices to condense.

The yellow lines on the map represent the boundaries between the plates that make up Earth's lithosphere.

From an airplane, you can detect most infrared light, which is absorbed by Earth's atmosphere.

The isotope 14C has two more neutrons in its nucleus compared to 12C, making it heavier.

When an electron in an atom jumps from a higher-energy orbital to a lower one, it releases a photon of light.

When an electron absorbs a photon of light, it jumps from a lower-energy orbital to a higher one.

A light curve shows how a star's brightness changes over time. It can reveal the star's period of variability, indicating a possible companion star or planet.

The Sun is a star, contains 98% of the solar system's mass, is primarily composed of hydrogen and helium, and has a diameter about 5 times that of Earth.

Mercury's surface temperature is hot enough to melt lead, even on its night side. It rotates three times for every two orbits around the Sun.

Accretion is the process where planetesimals grow by colliding and sticking together, forming larger bodies like planets.

Telescopes in space provide clearer images (unaffected by Earth's atmosphere) and can observe wavelengths of light not reaching the ground.

Mercury, Venus, Earth, and Mars are considered terrestrial planets, being mostly rocky with solid surfaces.

The Moon is believed to have formed when a Mars-sized object collided with Earth, ejecting material that formed the Moon.

Better angular resolution means a telescope can see more detail in images due to its ability to distinguish objects that are close together.

The solar nebula collapsed due to gravity, leading to increased rotation and heating. The collapse resulted in a flattened disk orbiting the Sun.

Lunar maria are relatively smooth, flat plains on the Moon formed by ancient volcanic eruptions.

Olympus Mons is a massive shield volcano located on Mars, making it the largest volcano in our solar system.

Convection involves the transfer of heat through the movement of fluids (liquids or gases). Hotter, less dense material rises, while cooler, denser material sinks.

Radiometric dating indicates that Moon rocks and meteorites are approximately 4 billion years old.

Mercury and Earth's Moon show evidence of heavy cratering, which suggests they've been bombarded by asteroids and comets.

Earth and Venus have substantial atmospheres, while Mercury and Earth's Moon have very thin or no atmospheres.

Earth's magnetic field is generated by the movement of molten iron in its core. This field protects us from harmful solar radiation.

Four primary processes shape planetary surfaces: tectonics (plate movement), impacts (collisions), volcanism (eruptions), and erosion.

The primary gases in Earth's atmosphere are nitrogen (78%) and oxygen (21%).

Atmospheric pressure decreases as altitude increases because the weight of the air above you lessens.

Without the greenhouse effect, Earth's average temperature would be far colder, making it uninhabitable.

A higher albedo means a surface reflects more sunlight, leading to a cooler temperature.

Atmospheric pressure is caused by the weight of the air above a given point.

Comets are remnants from the early solar system, composed of ice and dust, and originate from regions like the Kuiper belt and Oort cloud.

Pluto is classified as a dwarf planet, belonging to a group of objects called Kuiper belt objects.

Comets can originate from the Oort cloud, a spherical cloud of icy objects far beyond Pluto, and can travel towards the Sun from various directions.

Major asteroid or comet impacts capable of causing mass extinctions are estimated to happen every 100 million years.

It's implausible for asteroids to have active volcanoes because they are too small to retain enough internal heat for geological activity.

The asteroid belt beyond Jupiter is sparse because there was less rocky material available at those distances and Jupiter's gravity disrupted any potential planet formation.

Water vapor and carbon dioxide are significant greenhouse gases in Earth's atmosphere, trapping heat and warming the planet.

Earth's atmosphere is layered from bottom to top: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Infrared radiation emitted by Earth's surface heats the troposphere from below, driving weather patterns.

The stratosphere is heated primarily by ultraviolet radiation from the Sun.

The blue color of the sky is caused by the scattering of sunlight by molecules in the atmosphere, with blue light scattering more than other colors.

Earth's magnetosphere protects us from the solar wind, a stream of charged particles from the Sun.

Earth's global circulation pattern is driven by convection due to uneven heating, Earth's rotation, and the Coriolis effect.

Long-term climate change can be caused by changes in solar brightness, Earth's reflectivity, the tilt of its axis, and greenhouse gas abundance.

Earth's atmosphere primarily originated from outgassing, the release of gases from the planet's interior.

Carbon dioxide has dissolved in the oceans and been incorporated into rocks, reducing its abundance in Earth's atmosphere.

The Moon and Mercury have very thin or no atmospheres due to their low gravity and lack of volcanic activity.

Evidence suggests that Mars once had a thicker atmosphere, liquid water, and a warmer climate, but has lost its atmosphere due to solar wind stripping.

Moving Earth to Venus's orbit would likely lead to a runaway greenhouse effect, making Earth uninhabitable.

Without plants, the oxygen in Earth's atmosphere would eventually be used up in chemical reactions, decreasing over time.

It's plausible for a planet to have an oxygen-rich atmosphere without life, as oxygen can be created through non-biological processes.

Planets can change their orbits due to gravitational encounters with other objects, exchanging energy and angular momentum.

If each star in the Milky Way has at least one planet, there are likely over 100 billion planets in our galaxy.

The Sun's energy comes from nuclear fusion, a process where hydrogen atoms fuse to form helium, releasing massive amounts of energy.

The Sun is very dense in its core due to the weight of its outer layers pressing down, causing extreme pressure and temperature.

Nuclear fusion of hydrogen requires extremely high temperatures (millions of Kelvin) and high density, creating the conditions for atoms to fuse.

A hydrogen nucleus is a proton, a positively charged particle, which fuses into helium in the Sun's core.

If the Sun's core shrinks, the density and temperature would increase, leading to faster fusion and more energy output.

If the Sun's core fusion sped up, it would release more energy, causing the Sun to expand and brighten.

Photons travel through the Sun's radiation zone by being absorbed and re-emitted by atoms, slowly making their way outward.

By the time photons reach the Sun's surface (photosphere), they are mostly in the visible light spectrum.

We learn about the Sun's interior through observations of neutrinos, sunquakes, and computer models.

Sunspots are cooler regions on the Sun's surface with strong magnetic fields, appearing as dark spots.

The Sun's corona (outer atmosphere) has extremely high temperatures (millions of degrees) but is very thin and can be detected through x-rays.

The sunspot cycle is an 11-year cycle where the number of sunspots on the Sun increases and decreases.

Coronal mass ejections from the Sun can disrupt Earth's magnetic field, create auroras, damage satellites, and cause electrical power outages.

The Sun's mass can be determined by observing Earth's orbital period and distance from the Sun, using Newton's version of Kepler's Third Law.

If fusion in the Sun's core ceased, it would take thousands of years for the light created by past fusion reactions to reach Earth.

The number of sunspots peaks during solar maximum, a period of more intense solar activity.

The Sun's mass can be determined by observing Earth's orbital period and distance from the Sun, using Newton's version of Kepler's Third Law.

If the Sun's core fusion rate increased, it would lead to the Sun's core expanding and heating up.

Io is heated by tidal heating, caused by Jupiter's strong gravitational pull stretching and squeezing Io as it orbits.

Tidal heating increases with a moon's more elliptical orbit, larger size, and a larger companion planet.

Jupiter generates internal heat by shrinking and releasing gravitational potential energy, causing it to radiate more energy than it receives from the Sun.

Titan, a moon of Saturn, has a thick atmosphere and a surface with lakes and oceans of liquid methane and ethane.

Larger moons tend to be spherical due to their internal gravity, while smaller moons often have irregular shapes because their gravity is weaker.

Icy moons can be geologically active even if they are small because ice melts at lower temperatures than rock, and many experience tidal heating.

Asteroids are rocky bodies, varying in size, found primarily in the asteroid belt between Mars and Jupiter, orbiting the Sun.

The best way to determine an asteroid's density is by studying a sample of its material.

Most meteorites come from asteroids, remnants from the early solar system.

Comets formed from icy planetesimals in the outer solar system and orbit the Sun on long, elliptical paths, returning periodically.

A comet's nucleus is composed of ice and dust, resembling a dirty snowball.

If Earth passed through a comet's tail, it would likely result in a meteor shower, as Earth encounters the comet's debris.

Meteor showers occur annually when Earth passes through the orbit of a comet and encounters the debris left in its wake.

Comet tails always point away from the Sun because the solar wind pushes the gas and dust away from the comet.

The Kepler mission detected numerous extrasolar planets by observing their transits, or passing in front of their host stars, causing a dip in the star's brightness.

The planet's transit causes a dip in the star's brightness, allowing astronomers to estimate the planet's size, orbital period, and sometimes even its atmospheric composition.

For an alien to discover Earth using the transit method, their exoplanetary system would need to be located along the celestial equator, where Earth's transit path would be observable.

A star's back-and-forth motion with a period of 16 months indicates a planet orbiting it at a distance greater than 1 AU (Earth's distance from the Sun).

A planet's orbit can move inward due to gravitational encounters with other objects, where the planet transfers energy and angular momentum to the other object.

The Jovian planets (Jupiter, Saturn, Uranus, and Neptune) all have rings due to a combination of captured particles, moons disintegrating, and ongoing collisions between small moons and orbiting particles.

If Saturn were placed on a water planet, it would float because its average density is less than that of water.

Jupiter and Saturn are primarily composed of hydrogen and helium, while Uranus and Neptune have a higher proportion of heavier elements like oxygen and nitrogen.

If Jupiter were the size of a basketball, Earth would be about the size of a marble.

It typically takes several years for a spacecraft to travel from Earth to Jupiter.

Jovian planets are large, gaseous, have many moons, rotate quickly, and have rings.

Jupiter has a thick atmosphere, then liquid hydrogen, metallic hydrogen, and a solid core, composed of heavier elements.

Hydrogen and helium are the most abundant elements in the atmospheres of Jupiter and Saturn.

Water, methane, and ammonia are common hydrogen compounds found in the atmospheres of Jupiter and Saturn.

Jupiter's magnetic field is generated by the rapid rotation of its metallic hydrogen interior, flowing like a liquid metal.

Auroras are visible light displays in the sky, often near planetary poles, caused by charged particles from the Sun interacting with a planet's atmosphere and magnetic field.

Jupiter's weather is characterized by high-speed winds, low-density clouds, and thick clouds, driven by convection and internal heat.

Jupiter is slightly larger than Saturn despite having three times the mass due to gravitational compression, which makes its interior denser.

Observing Jovian planets in different wavelengths of light reveals different atmospheric layers, cloud types, and temperature variations.

Io, a moon of Jupiter, is the most geologically active object in our solar system due to intense tidal heating.

The whitish glow around the Space Shuttle's tail is caused by its exhaust gases interacting with the thin atmosphere at that altitude.

The diagram represents the greenhouse effect, where certain gases (e.g., carbon dioxide) trap heat radiated by the Earth's surface, warming the planet.

The graph indicates that the current level of carbon dioxide in our atmosphere is higher than at any time in the past 800,000 years, which is likely contributing to global warming.

The diagram shows a planet transiting its star, causing a dip in the star's brightness as the planet passes in front of it.

Pushing a swing at just the right frequency, or resonance, causes it to swing higher due to the transfer of energy.

Asteroids in the asteroid belt are concentrated into patterns by resonances with Jupiter's gravity.

The graph shows the light curve of a star during a transit, revealing that the planet blocks about 2.5% of the star's light.

The graph shows the number of extrasolar planets detected with different orbital periods, suggesting that there are more planets with longer orbital periods.