Astronomy Bloch

How did this place get here? Universe – everything that exists in any place – all the space, matter, and energy in existence Scientists believe the universe is ~10 – 17 billion years old The universe began with the big bang

The Big Bang Big Bang – In the beginning of time, all matter and energy in the universe was concentrated in a small area. Then, there was a gigantic explosion and matter began to organize into subatomic particles and elements.

Evidence that supports the Big Bang: Most galaxies in the universe appear to be moving away from us, suggesting that the universe is expanding from a single point

Doppler effect – the apparent wavelength shifting of electromagnetic energy (such as visible light), caused by the relative motion between the energy source and the observer Red shift – Occurs when a source of energy is moving away from an observer. Electromagnetic spectrum shifts toward longer wavelengths (red)

Blue shift – Occurs when a source of energy is moving towards an observer. Electromagnetic spectrum shifts toward shorter wavelengths (blue)

Evidence? Scientists examine the electromagnetic radiation emitted by stars and other celestial objects to see if the universe is expanding

What are those bright lights in the sky? Galaxy – A collection of billions of stars, gas, and dust held together by gravity.

Looking toward the center of the Milky Way Galaxy

Phoenix (Dwarf Galaxy)

ESO 325-G004 (Elliptical Galaxy)

Andromeda (Spiral Galaxy)

Messier 102 (Pinwheel Galaxy)

NGC 4414 (Spiral Galaxy)

The Sombrero Galaxy (Unbarred Spiral Galaxy)

NGC1300 (Spiral Galaxy)

Hoag’s Object (Ring Galaxy)

Ngc 5866 (Lenticular Galaxy)

The Antennae Galaxies colliding

Whirlpool Galaxy (Spiral Galaxy)

ESO 510-G13 (Warped Spiral Galaxy)

Messier 82 (Starburst Galaxy)

Bode’s Galaxy (Spiral Galaxy)

Sunflower Galaxy (Spiral Galaxy)

Tadpole Galaxy (Disrupted Barred Spiral Galaxy)

The Sculptor Galaxy (Disc Galaxy)

What are those bright lights in the sky? Stars - a large ball of gas held together by gravity that produces tremendous amounts of energy via nuclear fusion. Stars are thought to have originated from clouds of gas and dust left over from the big bang. Gravity causes the gas and dust to “clump up”

Main sequence stars 90 percent of stars are located here. (Our sun is located here.) Most stars spend the majority of their lifespan at this location. These stars tend to be of average size. As temperature increases, luminosity increases. Luminosity will increase from red to blue-white A red dwarf is the coolest and smallest type of main sequence star.

Giant stars 10x the diameter of the sun High luminosity but cool temperature Late stage of development into a main sequence star

Supergiants Diameter is 100 to 1000x the diameter of the sun Tend to explode in an event called a supernova High luminosity, high temperature The brightest and the highest temperature are the blue supergiants

White Dwarfs Small – about the size of the Earth High temperature, low luminosity

Black Dwarfs Dead Stars

What are planets? Planet – largest non-star celestial object that revolves around a star. There are over 100 known planets, 8 which revolve around our Sun

Different types? Terrestrial planets – the planets (Mercury, Venus, Earth, and Mars) that are Earth-like. They are relatively close to the Sun, mostly solid, small size, and high density Jovian planets – planets that are far from the Sun, largely gaseous, have relatively large diameters, many moons, rings, and low densities. (Jupiter, Saturn, Uranus, and Neptune)

The rotation of all the planets must follow scientific laws devised by a famous astronomer named Johanas Kepler

Kepler’s First Law Law 1: The orbit of a planet around the Sun is an ellipse with the Sun's center of mass at one point Planets do not have circular orbits, they follow an oval shape called an ellipse. Within an ellipse there are two fixed points called foci. They are an equal distance apart.

What is eccentricity? The degree of “ovalness” of an ellipse is measured by eccentricity. Eccentricity of an ellipse can be calculated as such:

Kepler’s Second Law Law 2: A line joining a planet/comet and the Sun sweeps out equal areas in equal intervals of time

How do we know how the Earth moves? Geocentric model – assumes that the Earth is stationary and that all celestial objects revolve around it. Many earlier cultures followed this belief. Heliocentric model – assumes that the Sun is stationary and that the planets (including Earth) revolve around it.

Evidence for a heliocentric model Constellations ( a group of stars that form a pattern) that are present in the sky at different times of the year and change. Seasonal changes throughout the year (we have four seasons as opposed to one season all year)

Evidence for the Earth rotation: The Foucault pendulum - a freely swinging pendulum whose path appears to change in a predictable way, thus providing evidence for the Earth’s rotation Coriolis Effect – the deflection of all moving particles of matter (such as winds and surface ocean currents) at Earth’s surface to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The wind is actually going in a straight line, but the Earth is moving beneath it.

Why is the moon so important? Moon – a body that orbits a planet or an asteroid as those objects orbit the sun Our moon revolves around the Earth in an elliptical orbit over the course of 27.3 days and is tilted 5

Why does the moon change? Various amounts of lighted moon as seen from Earth in a cyclic pattern is known as the moon phases

Important Facts The moon is highly influential for the cyclic rise and fall of the tides – the gravitational force between the Earth and the moon cause the oceans to bulge. Lunar eclipse – when the moon revolves into the shadow of the Earth, at the full moon phase Solar eclipse – under rare conditions at the new moon phase, the moon can just barely block out the sun, casting a shadow on the Earth