Question 1 of 10Correct: 0
Why do you see a distant star's past when you look at it?
Does a star's old light mean the star itself is gone?
Why do stars twinkle?
Why don't planets twinkle?
Why is a blue star hotter than a red one?
Why do stars often look like white dots?
What sets a star's birth in motion?
What determines a star's fate?
What remains at the center after a massive star explodes?
Where did the heavy elements on Earth come from?
Questions from 5 articles
Each one takes 2 minutes to read. Stuck on a question? Peek at the article.
Why, when you look at the stars, you see the past0/2Why Stars Twinkle but Planets Don't0/2Why stars are different colorsin the app0/2How Stars Are Born0/2What remains after a star explodesin the app0/2
A quiz after every article
In the app, a quiz like this follows every article, and every read grows your streak and level.
Answers and explanations10 questions
- Why do you see a distant star's past when you look at it? Its light doesn't reach you instantlyLight needs time to reach your eye, so distant objects appear as they were earlier.From “Why, when you look at the stars, you see the past”
- Does a star's old light mean the star itself is gone? No, almost all visible stars still existLight can be old, but stars live much longer than the time their light usually takes to reach us.From “Why, when you look at the stars, you see the past”
- Why do stars twinkle? Because atmospheric irregularities refract lightA star is a point, so its entire beam is shifted at once.From “Why Stars Twinkle but Planets Don't”
- Why don't planets twinkle? Their disk is larger, so fluctuations in different parts average outStars don't twinkle from space either: outside the atmosphere, there is no distortion.From “Why Stars Twinkle but Planets Don't”
- Why is a blue star hotter than a red one? Its radiation peak shifts to shorter wavelengthsThe hotter the surface, the shorter the wavelength at peak emission - which is why blue stars are hotter than red ones.From “Why stars are different colors”
- Why do stars often look like white dots? In dim light, your eye barely sees colorWhen light is scarce, the part of your retina that cannot see color takes over, and stars look white.From “Why stars are different colors”
- What sets a star's birth in motion? An external push that disrupts the cloud's balanceOften, it's an explosion of a neighboring star: one star's death triggers the birth of others.From “How Stars Are Born”
- What determines a star's fate? Its mass at the startIt determines whether the star will ignite at all, how long it will live, and how it will end.From “How Stars Are Born”
- What remains at the center after a massive star explodes? A neutron star or black hole, depending on its massThe core collapses in fractions of a second and is compressed to a density unimaginable under ordinary conditions.From “What remains after a star explodes”
- Where did the heavy elements on Earth come from? They spread through the galaxy in star explosionsThere is simply no other way to deliver iron and heavier elements.From “What remains after a star explodes”