PHY 201 Module 5

The first technique that allowed astronomers to find exoplanets involved:

measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets

A _____ occurs when many meteors appear to radiate from one point in the sky; produced when Earth passes through a cometary dust stream

meteor shower

A _____ is a portion of a meteor that survives passage through the atmosphere and strikes the ground

meteorite

A _____ is a fundamental particle that has no charge and a mass that is tiny relative to an electron; it rarely interacts with ordinary matter and comes in three different types

neutrino

According to the formula E=mc2,

a little bit of mass can be converted into a substantial amount of energy

A _____ is a particle with the same mass as an electron, but positively charged

positron

Astronomers first detected the presence of a wind of particles coming from the Sun by

by noting the wind's effects on the tails of comets

Astronomers call the vast, rotating cloud of vapor and dust from which the solar system formed:

the solar nebula

Sunspots are darker than the regions of the Sun around them because

they are cooler than the material around them (although still very hot compared to Earth temperatures)

_____ is a flow of hot, charged particles leaving the Sun

solar wind

Which of the following is a way for astronomers to learn more about the interior of the Sun?

study the oscillations (pulsations) of the Sun's surface

A _____ is a large, dark feature seen on the surface of the Sun caused by increased magnetic activity

sunspot

Astronomers now believe that the differences in composition among the planets reflect what characteristic in the early solar system

temperature

Which of the following is not a characteristic that worlds in our solar system have in common:

that all the planets have solid surfaces on which we can see impact craters

The _____ (of the Sun) is the outer (hot) atmosphere of the Sun

corona

Which of the following statements about the Sun's photosphere is NOT TRUE?

The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward)

How can astronomers measure the age of a meteorite that fell from the skies?

They measure the amount still left of radioactive materials in the meteorite, and how much has turned into decay products

Coronal Mass Ejections from the Sun have many serious effects on or near the Earth. Which of the following is NOT one of these effects?

causing huge cyclones around the equator of the Eart

One of the best proofs that our theory of how the solar system formed is correct is that astronomers now observe

disks around other stars which show evidence of gaps where planets may be forming

In the Sun, when a positron and an electron collide, they will produce:

energy in the form of a gamma ray

An _____ is a planet orbiting a star other than our Sun

exoplanet

If the "fuel" for nuclear fusion is nuclei of hydrogen, and the Earth's oceans are filled with hydrogen atoms in water all being jostled together, why isn't there a lot of fusion happening in our oceans?

for hydrogen nuclei to fuse, they must get very close to each other, which the nuclei in the oceans cannot do

_____ refers to the building up of heavier atomic nuclei from lighter ones

fusion

The most common element in the Sun is

hydrogen

Some of the early planetesimals that formed the solar system still survive today. Where would you find such planetesimals?

in the asteroid and Kuiper belts

The Sun is an enormous ball of gas. Left to itself, a ball of so many atoms should collapse under its own tremendous gravity. Why is our Sun not collapsing?

nuclear fusion in the core keeps the temperature and the pressure inside the Sun at a high enough level so that gravity is balanced

The _____ is the region of the solar (or stellar) atmosphere from which continuous radiation escapes into space

photosphere

What mechanisms do astronomers believe is responsible for making the Sun's outer atmosphere so much hotter than its photosphere?

the Sun's magnetic field interacting with the charged particles that make up the atmosphere

The process of fusion that keeps our Sun shining begins with which building blocks?

two protons

How do astronomers know what the outer layers of the Sun are made of?

we take an absorption line spectrum of the Sun, and the absorption lines tell us what elements are present in the outer layers