Earth and Space Flashcards

Flashcards about Earth, the Solar System, Stars, and the Universe

What causes the periodic cycle of day and night on Earth?

The Earth's rotation on its tilted axis every 24 hours changes the position of each place on Earth relative to the sun.

In which direction does the Earth rotate when viewed from the North Pole?

Anticlockwise.

What two factors combine to create the seasons?

The Earth's orbit around the Sun and the tilt of the Earth's axis.

What occurs when one hemisphere is tilted towards the sun?

That hemisphere experiences spring or summer with more daylight hours.

What are the equinoxes?

Points in Earth's orbit when daylight hours and darkness are equal in both hemispheres.

How long does it take for the moon to orbit the Earth?

Approximately 1 month.

What causes the phases of the moon?

The varying amount of sunlight reflected by the moon as it orbits the Earth creates the lunar phases.

What is the formula to calculate the average speed of a body in orbit?

velocity = (2 * pi * average radius of orbit) / orbital period

What makes up the solar system?

A gravitationally bound system made up of the Sun and everything that orbits it.

What is the speed of light?

3 × 10^8 m/s

What is the equation for finding the time taken for light to travel between objects in the Solar System?

time = distance / speed of light

What is the most massive object in the solar system?

The sun.

What defines a planet?

It orbits the sun and has a gravitational field strong enough to pull in all nearby objects.

mnemonic for remembering the planets in order

My Very Easy Mnemonic Just Speeds Up Naming.

How does the accretion model explain the composition of the planets?

Inner planets formed from heavier elements in the hotter region and outer planets formed from lighter molecules in the cooler region.

What distinguishes minor planets from the eight major planets?

Minor planets do not have a gravitational field strong enough to clear their orbits of other objects.

Give examples of minor planets.

Dwarf planets (like Pluto), asteroids (in the asteroid belt), and comets.

natural satellites

Naturally occurring bodies that orbit a planet (e.g., moons).

What trends are observed in planets further from the sun?

Larger orbital distance, longer orbital duration, slower orbital speed, lower density, and lower surface temperature.

How does distance affect the gravitational field strength of a planet or the Sun?

The strength of the gravitational field decreases as distance increases.

What shape are the orbits of bodies orbiting the Sun?

Elliptical (oval-shaped).

How does a body's speed change as it orbits the sun?

These bodies travel faster when closer to the Sun because the orbital radius decreases.

What elements primarily make up the Sun?”,

Hydrogen and helium.

How does the Sun release energy?

Through nuclear reactions (nuclear fusion).

Milky Way

A galaxy containing billions of stars, including the Sun.

How are astronomical distances measured?

In light-years, based on the time it takes light to travel between objects.

a light-year

The distance light travels in one year (9.5 × 10^15 m).

Describe the life cycle of a star.

Nebula → Protostar → Stable Star → Red Giant/Supergiant → Planetary Nebula/Supernova → White Dwarf/Neutron Star/Black Hole.

What force balances gravitational attraction in a stable star?

Outward force of gas pressure from nuclear fusion.

What is redshift?

An increase in the observed wavelength of electromagnetic radiation emitted from an object which is receding.

What does redshift in the light from distant galaxies indicate?

The Universe is expanding.

What is the Hubble constant?

The ratio of a galaxy’s speed moving away from Earth to its distance from Earth (H0 = v/d).

How can the Hubble constant be used?

To estimate the age of the universe (1/H0).

What is cosmic microwave background radiation (CMBR)?

Microwave radiation observed at all points in space, a remnant of the early Universe.

What theory does the existence of CMBR support?

The Big Bang Theory.