Astronomy

Question 1

Describe the motion of the Sun, Moon and stars that appears to an observer on Earth.

Answer 1

It appears to rotate around us.

Question 2

Describe the main differences between the Sun-centered (heliocentric) and Earth-centered
(geocentric) models.

Answer 2

Heliocentric models state that the sun is at the centre, while geocentric models state the earth is at the centre.

Question 3

Explain the difference between revolution and rotation.

Answer 3

A revolution is an orbit around the sun, while a rotation is a spin around the axis.

Question 4

Describe units of distance relevant for studying space (AU, light year)

Answer 4

Km is used for distances on Earth.
AU is used for distances within our solar system.
Light year is used for distances outside our solar system.

Question 5

What are the different parts of the sun?

Answer 5

Core, radiative zone, convective zone, photosphere, chromosphere, and corona.

Question 6

Describe how the sun contributes to favourable conditions on Earth for life.

Answer 6

Without the Sun’s heat and light, the Earth would be a lifeless ball of ice-coated rock. The Sun warms our seas, stirs our atmosphere, generates our weather patterns, and gives energy to the growing green plants that provide food and oxygen for life on Earth.

Question 7

What is a lunar eclipse?

Answer 7

Occurs when the Moon passes directly behind Earth and into its shadow.

Question 8

What is a solar eclipse?

Answer 8

Occurs when the moon gets between Earth and the sun, and the moon casts a shadow over Earth

Question 9

How does Earth’s positions affect seasons?

Answer 9

The seasons are caused as the Earth, tilted on its axis, travels in a loop around the Sun each year. Summer happens in the hemisphere tilted towards the Sun, and winter happens in the hemisphere tilted away from the Sun.

Question 10

What are the different solstice and equinoxes?

Answer 10

Vernal equinox(about March 21): day and night of equal length, marking the start of spring
Summer solstice (June 20 or 21): longest day of the year, marking the start of summer
Autumnal equinox(around September 23): day and night of equal length, marking the start of
autumn
Winter Solstice (December 21 or 22): shortest day of the year, marking the start of winter

Question 11

What is an equinox?

Answer 11

Equinox meaning: the time or date (twice each year) at which the sun crosses the celestial
equator, when day and night are of equal length (about September 22 and March 20).

Question 12

What is a solstice?

Answer 12

Solstice meaning: Solstice either of the two times in the year, the summer solstice and the winter solstice, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days.

Question 13

What are the different phases of the moon?

Answer 13

New Moon
Waxing Crescent
First Quarter
Waxing Gibbous
Full
Waning Gibbous
Third Quarter
Waning Crescent
Dark Moon

Question 14

What is the order of planets from the sun?

Answer 14

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Question 15

What can create surface features on planets in our solar system?

Answer 15

As hot surfaces cooled, they fractured and created great chasms. Water, ice, wind, and volcanoes can also erode surface.

Question 16

What are ring systems?

Answer 16

All gas planets have rings. Saturn has thousands of bright reflective rings, while the rest have a few dark rings. Rings are made of ice and rock particles ranging in size. Collisions among these particles keep the rings thin. Rings can be left over from the planet’s formation or debris from the destruction of moons.

Question 17

What are moons?

Answer 17

The more than sixty moons of the solar system are a diverse collection of worlds. Two are larger than the planet Mercury. Some have ancient cratered surfaces, while others are geologically active. Many smaller moons appear to be asteroids or comets captured by the gravity of their planet.

Question 18

What are atmospheric storms?

Answer 18

Great atmospheric storms occur on all the gas giants. The rapid rotation of these planets stretches weather systems into zones that encircle them. High winds blow in opposite directions at the edges of the zones and feed energy into enormous rotating storms. Though they resemble Earth’s hurricanes, these storms are far more powerful and up to a hundred times larger.

Question 19

What are asteroids?

Answer 19

a small rocky body orbiting the sun

Question 20

What are meteors?

Answer 20

dust and ice from the trail of comets

Question 21

What are comets?

Answer 21

a ball of mostly ice that moves around in outer space

Question 22

What are the properties of stars that astronomers can determine?

Answer 22

Brightness, colour, surface temperature, size, and mass.

Question 23

What are the characteristics that determine brightness?

Answer 23

Luminosity and magnitude.

Question 24

What is luminosity?

Answer 24

The amount of light that a star radiates. The size of the star and its surface temperature determine its luminosity.

Question 25

What is magnitude?

Answer 25

Apparent magnitude of a star is its perceived brightness, factoring in size and distance, while absolute magnitude is its true brightness irrespective of its distance from earth.

Question 26

What determines the colour of a star?

Answer 26

A star’s color depends on its surface temperature. Cooler stars tend to be redder in color, while hotter stars have a bluer appearance. Stars in the mid ranges are white or yellow, such as our sun. Stars can also blend colours, such as red-orange stars or blue-white stars.

Question 27

What is surface temperature?

Answer 27

Astronomers measure a star’s temperature on the Kelvin scale. Zero degrees on the Kelvin scale is theoretically absolute and is equal to -273.15 degrees Celsius. The coolest, reddest stars are approximately 2,500 K, while the hottest stars can reach 50,000 K. Our sun is about 5,500 K.

Question 28

What is size?

Answer 28

Astronomers measure the size of a given star in terms of our own sun’s radius. Thus, a star that measure 1 solar radius would be the same size as our sun. The star Rigel, which is much larger than our sun, measures 78 solar radii. A star’s size, along with its surface temperature, will determine its luminosity.

Question 29

What is mass?

Answer 29

A star’s mass is also measured in terms of our own sun, with 1 equal to the size of our sun. For instance, Rigel, which is much larger than our sun, has a mass of 3.5 solar masses. Two stars of a similar size may not necessarily have the same mass, as stars can vary greatly in density.

Question 30

What is the solar nebula theory?

Answer 30

As it relates to our own solar system, the nebular theory explains three observable facts. The first is that the planets all rotate in the same direction. The second is that they all orbit within 6 degrees of a common plane. The third is that all the terrestrial planets, which are those within the orbit of the Asteroid Belt, are rocky, while those outside it are gaseous. The theory also explains the existence of the Kuiper Belt – a region on the fringes of the solar system with a high concentration of comets.

Question 31

What is star formation?

Answer 31

Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as “stellar nurseries” or “star-forming regions”, collapse and form stars.

Question 32

What is the star cycle of a small to medium star?

Answer 32

Nebula, main sequence star, red giant, planetary nebula, white dwarf.

Question 33

What is the star cycle of a large star?

Answer 33

Nebula, main sequence star, red supergiant, supernova, neutron star.

Question 34

What is the star cycle of an extremely large star?

Answer 34

Nebula, main sequence star, red supergiant, supernova, black hole.

Question 35

What is the Big Bang theory?

Answer 35

the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now

Question 36

What is star spectral analysis?

Answer 36

Using a given absorption spectrum of various elements and a star, be able to determine which elements exist within that star.
Each chemical element has its own spectral signature.