Science Earth and Space Science Flashcards

During a lunar eclipse, Earth's shadow has two distinct regions: the umbra and the penumbra. An observer on the Moon standing in the penumbra would see which of the following?

Answer: A partial solar eclipse caused by Earth

From the penumbra, Earth only partially covers the Sun — so an observer there would see a partial solar eclipse. Only someone standing in Earth's umbra would see the Sun completely blocked. The penumbra is the region where Earth casts a partial shadow, allowing some sunlight through.

The Coriolis effect influences large-scale wind patterns on Earth. Which of the following best explains WHY hurricanes rotate counterclockwise in the Northern Hemisphere?

Answer: Earth's rotation causes moving air masses to deflect to the right, drawing air counterclockwise around a low-pressure center

In the Northern Hemisphere, the Coriolis effect deflects moving objects (including air) to the right relative to their direction of motion. Air rushing into a low-pressure center gets deflected rightward, which creates a counterclockwise (cyclonic) rotation around the eye of a hurricane. The deflection is a consequence of Earth spinning on its axis.

A geologist finds a rock layer containing index fossils from two different species: one that lived 430–420 million years ago and another that lived 425–415 million years ago. What is the most precise age range she can assign to that rock layer?

Answer: 425–420 million years ago

The rock must have formed during a time when BOTH species were alive simultaneously. Species A existed 430–420 Mya and Species B existed 425–415 Mya. The overlapping window — when both were alive — is 425–420 million years ago. This is the principle of overlapping ranges used in biostratigraphy to narrow fossil dating.

On Earth, the weight of an object equals the gravitational force pulling it toward Earth's center. An astronaut weighs 800 N on Earth's surface. If she travels to a location twice Earth's radius from Earth's center (i.e., one Earth-radius above the surface), what will her weight be?

Answer: 200 N

Gravity follows an inverse-square law: F ∝ 1/r². If the distance from Earth's center doubles (from 1R to 2R), gravity decreases by a factor of 2² = 4. So her weight becomes 800 N ÷ 4 = 200 N. Note the question specifies distance from Earth's center, not altitude above surface.

Scientists studying a mid-ocean ridge discover that rocks closest to the ridge center have the youngest magnetic signatures, while rocks farther away are progressively older and show alternating bands of normal and reversed magnetic polarity. This pattern MOST directly supports which concept?

Answer: Seafloor spreading and periodic reversals of Earth's magnetic field

The symmetric striping of normal and reversed magnetic polarity on either side of a mid-ocean ridge is the definitive evidence for seafloor spreading — new crust forms at the ridge and records Earth's magnetic polarity at that time, then spreads outward. Periodic geomagnetic reversals create the alternating bands. This was one of the key proofs of plate tectonics.

Venus and Earth are nearly identical in size and composition, yet Venus has a surface temperature of about 465°C while Earth averages 15°C. Earth's atmosphere is 78% nitrogen and 21% oxygen; Venus's is about 96% carbon dioxide. Which of the following BEST explains the extreme temperature difference?

Answer: Venus's thick CO₂ atmosphere creates a runaway greenhouse effect that traps far more outgoing infrared radiation than Earth's atmosphere

Although Venus is closer to the Sun, it actually reflects more sunlight (higher albedo) due to its cloud cover, so solar input alone doesn't account for the difference. The primary driver is Venus's dense CO₂ atmosphere, which absorbs and re-emits infrared radiation far more efficiently than Earth's atmosphere — a runaway greenhouse effect. This traps heat so effectively that Venus is actually hotter than Mercury, despite Mercury being closer to the Sun.