CSET Science: Earth and Space Sciences Flashcards

What is the primary energy source that powers the Sun?

Answer: Nuclear fusion of hydrogen nuclei into helium

The Sun generates energy through nuclear fusion in its core, where hydrogen nuclei fuse to form helium, releasing enormous energy according to E=mc².

What does the Hertzsprung-Russell (H-R) diagram plot?

Answer: Stellar luminosity versus surface temperature

The H-R diagram plots stars according to their luminosity on the vertical axis and surface temperature on the horizontal axis, revealing patterns in stellar classification and evolution.

According to current scientific understanding, what is the approximate age of the universe?

Answer: 13.8 billion years

Measurements of cosmic microwave background radiation and the universe's expansion rate indicate an age of approximately 13.8 billion years since the Big Bang.

What causes the phases of the Moon as observed from Earth?

Answer: The changing angle from which observers on Earth view the sunlit half of the Moon

As the Moon orbits Earth, observers see different portions of its sunlit half depending on the geometric angle between the Sun, Moon, and Earth, creating the phases.

Which type of galaxy is characterized by a central bulge surrounded by a flat rotating disk with spiral arms?

Answer: Spiral galaxy

Spiral galaxies, like the Milky Way, feature a central bulge of older stars surrounded by a flat disk with spiral arms that contain stars, gas, dust, and active star formation.

What causes a solar eclipse?

Answer: The Moon passes directly between Earth and the Sun

A solar eclipse occurs when the Moon passes between Earth and the Sun, casting a shadow on Earth's surface and blocking sunlight from observers in that shadow.

Kepler's Third Law of planetary motion states that:

Answer: The square of a planet's orbital period is proportional to the cube of its semi-major axis

Kepler's Third Law establishes that T² ∝ a³, meaning planets farther from the Sun have proportionally longer orbital periods than those closer to it.