Today Phil’s explaining the stars and how they can be categorized using their spectra. Together with their distance, this provides a wealth of information about them including their luminosity, size, and temperature. The HR diagram plots stars’ luminosity versus temperature and most stars fall along the main sequence, where they live most of their lives.

Chapters:
Introduction: Stars
Stellar Spectra
Star Classifications
Why Are There No Green Stars?
Luminosity Depends on Size and Temperature
The HR Diagram
Main Sequence Stars
Other Stars on the HR Diagram
Review

Phil takes us for a closer (eye safe!) look at the two-octillion ton star that rules our solar system. We look at the sun's core, plasma, magnetic fields, sunspots, solar flares, coronal mass ejections, and what all of that means for our planet.

Chapters:
Introduction: Our Sun
The Sun's Core
Convection
Photosphere
The Corona & Solar Wind
How long does it take for light to reach the Sun's surface?
Plasma & The Sun's Magnetic Fields
Sunspots & Faculae
Solar Flares & Coronal Mass Ejections (CMEs)
The Earth & Solar Eruptions
Review

Today Phil explains how telescopes work and offers up some astronomical shopping advice.

Chapters:
Introduction
How do Telescopes Work?
Refraction
Magnification
Resolution
Reflectors
What Kind of Telescope Should You Buy?
Technology and the Light Spectrum
Review

Today Phil explores the world of tides! What is the relationship between tides and gravity? How do planets and their moons become tidally locked? What would happen if you were 300km tall? Important questions.

Chapters:
Introduction
Gravity Over Distance
Tidal Force Parameters
Battle of the Bulges
High and Low Tides
Push & Pull
Tidal Lock
Sun Tides
Review

Today we’re rounding out our planetary tour with ice giants Uranus and Neptune. Both have small rocky cores, thick mantles of ammonia, water, and methane, and atmospheres that make them look greenish and blue. Uranus has a truly weird rotation and relatively dull weather, while Neptune has clouds and storms whipped by tremendous winds. Both have rings and moons, with Neptune’s Triton probably being a captured iceball that has active geology.

Chapters:
Introduction: Uranus
Uranus's Structure
Uranus's Atmosphere
Uranus's Weird Tilt
Uranus's Moons
Uranus's Rings
Neptune's Structure
Neptune's Atmosphere
Neptune's Magnetic Field & Rings
Triton: Neptune's Largest Moon
The Discovery of Neptune
Review

Venus is a gorgeous naked-eye planet, hanging like a diamond in the twilight -- but its beauty is best looked at from afar. Even though Mercury is closer to the sun, Venus is the hottest planet in the solar system, due to a runaway greenhouse effect, and has the most volcanic activity in the solar system. Its north and south poles were flipped, causing it to rotate backward and making for very strange days on this beautiful but inhospitable world.

Chapters:
Introduction: Venus
Venus's Phases
Transit of Venus
Venus's Atmosphere
How did Venus get so hot?
Venus's Slow Rotation & Retrograde Motion
Venus's Spherical Structure
Venus's Surface
Volcanic Activity on Venus
Review

Today Phil follows up last week’s look at the death of low mass stars with what comes next: a white dwarf. White dwarfs are incredibly hot and dense objects roughly the size of Earth. They also can form planetary nebulae: huge, intricately detailed objects created when the wind blown from the dying stars is lit up by the central white dwarf. They only last a few millennia. The Sun probably won’t form one, but higher mass stars do.

Chapters:
Introduction
White Dwarfs
Planetary Nebulae
How Do Planetary Nebulae Get Their Shape?
Structure and Color of Planetary Nebulae
Will the Sun Become a Planetary Nebula?
Review