38 Questions
What is the exponent rule when dividing like powers?
Subtract exponents
What is the unit of mass defined as the mass of the Sun?
Solar mass
What is the celestial sphere?
The sky surrounding the Earth with the Earth at the centre
What is the average Earth-to-Sun distance equal to?
1.5 × 10^8 km
What is the unit of distance equal to the distance light travels in one year?
Light-year
In scientific notation, what operation is performed on the exponents when multiplying numbers?
Add exponents
What is the distance at which the average radius of Earth's orbit subtends an angle of one arc-second equal to?
1 pc
When dividing numbers in scientific notation, what is done with the mantissas and exponents?
Divide mantissas and subtract exponents
What is the unit of measurement used to describe the wavelength of light?
Ångström
What is the speed at which a photon always moves in a vacuum?
3 × 10^8 m/s
What is the definition of wavelength?
The distance from one crest to the next
What is the relationship between frequency and wavelength?
f = λc
What type of wave is light?
Electromagnetic wave
What is a photon?
A type of particle
What is the unit of measurement used to describe the frequency of light?
Hertz
What is the dual nature of light?
Wave and particle
What is the Doppler effect used for in astronomy?
To determine the velocity of celestial objects
What happens to the wavelength of light when an object is approaching an observer?
It appears to be smaller
What is the equation that governs the Doppler effect?
vc = λ−λ/λ0
Why does a dark surface appear black when shone with light?
Because light does not reflect off the surface
What is the solar system composed of?
The eight planets, their moons, and smaller objects like asteroids, meteoroids, and comets
What type of planets are Mercury, Venus, Earth, and Mars?
Terrestrial planets
What is the current status of Pluto?
A dwarf planet
What is the order of the planets in our solar system, starting from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What is the formula to determine the distance to a star?
d = p
What is the purpose of constellations today?
They do not serve much purpose
What is the magnitude of the Sun?
-27
What is the relationship between the brightness of two stars that differ in magnitude by 1?
They differ by a factor of 2.51
What is the problem with Hipparchus's method of classifying the brightness of stars?
It is based on a subjective measure
What is the term used to describe the brightness of stars based on Hipparchus's method?
Apparent magnitude
What is the magnitude of Venus?
-4
How many official constellations are recognized today?
88
What is the primary reason for the rising and lowering of tides?
The gravitational pull of the Moon on the Earth is stronger on the near side
What is the significance of Kepler's second law of planetary motion?
It illustrates that the planet sweeps out equal areas in equal times
What is the shape of a planet's orbit according to Kepler's first law?
Elliptical
What is the relationship between the orbital period of a planet and the semi-major axis of its orbit?
The square of the orbital period is proportional to the cube of the semi-major axis
What is an application of Newton's second law in astronomy?
Studying binary stars
What is the result of the Moon's gravitational pull on the Earth's oceans?
The oceans compress near the poles and elongate near the equator
Study Notes
Exponent Rules
- When multiplying like powers, add exponents.
- When dividing like powers, subtract exponents.
Scientific Notation
- To multiply numbers in scientific notation, multiply the mantissas and add the exponents of the powers of ten.
- To divide numbers in scientific notation, divide the mantissas and subtract the exponents of the powers of ten.
Units of Measure in Astronomy
- Distances are often measured in Astronomical Units (AU), light-years (ly), or parsecs (pc).
- 1 AU is defined as the average Earth-to-Sun distance, which is 1.5 × 10^8 km.
- 1 light-year is defined as the distance light travels in one year, which is 9.5 × 10^12 km.
- 1 parsec is defined as the distance at which the average radius of Earth's orbit subtends an angle of one arc-second, which is about 3.26 ly.
- Mass is often measured in solar masses, with 1 solar mass being the mass of the Sun, which is 1.99 × 10^30 kg.
Celestial Sphere
- The celestial sphere is a conceptual sphere surrounding the Earth, with the Earth at its center.
- The celestial sphere has an equator and north and south poles, which can be imagined to be extensions of the Earth's equator and poles projected onto the celestial sphere.
Tides
- The Moon exerts a gravitational pull on the entire Earth, causing a bulge in the Earth's oceans.
- This bulge results in rising and lowering of tides.
Kepler's Laws
- Planets follow elliptical orbits with their host star at one focus.
- Planets sweep out equal areas in equal times.
- The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
Light
- Light has a dual nature, existing as both a particle (photon) and a wave (electromagnetic wave).
- Wavelength (λ) is the distance from one crest to the next, or one trough to the next.
- Frequency (f) is the number of pulses of light per second, and is related to wavelength by: f = λc.
- The Doppler effect causes the wavelength of light to appear shorter when approaching an observer and longer when receding from an observer.
The Solar System
- The solar system consists of eight planets and their moons, as well as smaller objects like asteroids, meteoroids, and comets.
- The planets in our solar system, in order of distance from the Sun, are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Test your understanding of multiplying and dividing numbers in scientific notation, applying exponent rules to add and subtract exponents.
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