MAIN REVIEW OF ALL TOPICS FOR EXAM #2

What is the main purpose of telescopes?

To collect as much light as possible in the shortest possible time

What do you need for telescopes and why?

You need large mirrors or lens because you are collecting something and want the largest area

What is the equation for angular resolution?

Lamda(wavelength of light)/size

Why are most modern telescopes reflections?

Because their are easier to maintain and manufacture and they suffer less physical effects like absorption and friction

What do telescopes use Imaging for?

To create nice images

What do telescopes use spectroscopy for?

To measure the spectrum of an object

What do telescopes use time monitoring for?

to do long term monitoring of an object, like its radiation over time

What can you see with imaging?

You can see colors of objects (i.e.: blue objects-high energy and high temp, red objects-low energy and low temp)

Why do we use spectroscopy?

to measure spectral lines that are unique to individual elements

What does time monitoring do?

It observes the changes over time of objects

What are some ground based telescopes?

Optical and radio telescopes

What are some space based telescopes?

X-ray, gamma rays, UV

How do we improve angular resolution of telescopes?

Through adaptive optics and the use of interferometry, which counteracts interference from atmosphere

What are the 3 main types of spectra?

1. Emission/Discrete

2. Continuous

3. Absorption

What is the emission/discrete spectrum?

Nice bright lines separated with black/no background (like a picket fence)

What is the continuous spectrum?

A spread of colors from red to blue with no breaks in between

What is the absorption line spectrum?

A combination of the emission and continuous spectrum, continuous background with black gaps

How do we get the emission/discrete spectrum?

From low density material (like gasses)

How do we get continuous spectrum?

From hot and high dense materials (like solids)

How do we get an absorption spectrum?

From a combination of both emission and continuous, low density + hot temperature materials (like liquid). Get what’s left over from the lights absorbed by low density but color background from high temp

What the ranking of density from highest to lowest?

1. Solid

2. Liquid

3. Gas

What does the continuous spectrum depend on?

Temperature and substance. The higher the temp, the higher the scale, and vice versa

What are spectral lines?

They are unique fingerprints for elements because of the atomic structure of that element

What does spectral lines tell us?

They tell us about energy levels (and excess energy shows up as discrete lines)

What are spectral lines used for?

They are used to determine velocity and direction of astrophysical objects by deploying the Doppler effect

What is the Doppler effect?

It is the changes in wavelength or frequency by virtue of relative motion

How does the Doppler effect work?

If an object moves from its position to the red end, then the object is moving away from us. If it moves to the blue end it is moving towards us.

How do we learn about the surface temperature of an object?

By looking at its spectrum

Why is the sun a star?

Because it produces energy through nuclear fusion

What is the sun dominant in?

Mass, size, and radiation

What is the surface temperature of the sun?

5700 degrees Kelvin (Sun’s core is much hotter)

What is sun made of?

hydrogen, helium, and some plasma

How does the sun stay balanced?

between gravitation and radiation pressure

How does gravitation and radiation pressure work together to keep the sun stable?

The gravitation pushes the mass inwards due to gravity and the radiation pressure holds up the mass and pushes it out

How does sun convert hydrogen to helium and energy in core?

Through nuclear fusion by E=mc²

How does the proton-proton chain work?

4 protons converts to helium +energy + postrinos + neutrinos

How do the 4 protons stay together?

Becuase of the high temps and high density forces protons to stay together instead of repelling

What is the full sun’s structure list?

Solar Wind

Corona

Chromosphere

Photosphere

Core

Radiation Zone

Convection

What is the photosphere?

The thin outer layer of the sun

What are the 3 largest zones/layers of the Sun?

1. Core

2. Radiative zone

3. Convection zone

What happens in the core?

It generates a large amount of energy

What is in the radiative zone?

It has slightly lower temperature and density (but still a lot)

What hapens in the convection zone?

Where energy is transported by normal mechanism, motion of hydrogen molecues and plasma

What does Photon diffusion do?

It brings energy from core through radiative zone to outer layer

What does photon diffusion work with?

It works with scattering and absorption

How long does it take for energy to exit sun’s surface?

100,000 years

What are the outer layers of the Sun?

• Corona

• Solar Wind

What is the Corona?

A thin wispy layer, remains hidden because not very bright, but has high temperature from energetic electrons moving under action of magnetic field of sun

What is the solar wind?

It is particles from the sun made up of electrons, protons, and some helium ions.They leave the sun because of their high energy and velocity

How is the sun’s magnetic field primarily generated?

Through the differential rotation of the gasses plasma layers that include moving charges

What is the most dominant star in the solar system?

The sun by energy produced by nuclear fusion

What are the main 8 planets?

• Mercury

• Venus

• Earth

• Mars

• Jupiter

• Saturn

• Uranus

• Neptune

What are the dwarf planets?

• Pluto

• Eris

What are the two main groups of planets?

• Terrestrial

• Jovian

What are terrestrial planets?

inner planets, rock and metal-like

What are Jovian planets?

Outer planets, large gas-like

What are dwarf planets (3rd minor groups)?

small ice + rock-like

What are asteroids?

irregular shaped rock and metallic like objects . They occupy asteroid belt between orbits of mars and jupiter

Why are asteroids not spherical?

because they do not have enough as for gravity to shape them into spheres

What are the orbits of the planets?

They are nearly circular, but officially they are elliptical because of Kepler’s law

How do planets revolve?

They revolve around the Sun in the same direction and in a similar plane

How do planets rotate?

They rotate about their own individual axes

What do Uranus and Venus share in common?

They rotate in a different fashion

What is are important aspects of Mercury?

• Extreme variation in day and night temperature

• no atmosphere but posses small magnetic field

• Heavily cratered like Earth’s moon because of collisions during formation of solar system

What is the important aspect of Venus?

• The hottest planet because of greenhouse effect due to dense atmosphere of CO2

What is are important aspects of Earth?

Earth is the only habitable planet because of its atmosphere blocking harmful radiation such as UV rays

What is are important aspects of Mars?

• Mars has light atmosphere of CO2 and possesses a magentic field

• Its surface indicates the flow of water in its history

• Has 2 irregular shaped moons (probably captured asteroids from the asteriod belt)

What is are important aspects of Jupiter?

• It is the dominant Jovian planet According to mass and size

• It has a giant red spot on surface Which indicates storm-like features that has existed for centuries

• Has many moons (~67 to be exact)

• Has very faint rings

What is an important aspect of Saturn?

Its ring is not solid but made up of particle

What is an important aspect of Neptune?

It is the farthest from the sun