How can we know the size, composition, and atmospheric makeup of distant exoplanets? NASA explains the details in this Alien Atmospheres video.
By observing periodic variations in the parent star’s brightness and color, astronomers can indirectly determine an exoplanet’s distance from its star, its size, and its mass. But to truly understand an exoplanet astronomers must study its atmosphere, and they do so by splitting apart the parent star’s light during a planetary transit.
With its exceptional hearing, the red fox can detect when a small animal is scurrying around up to 3 feet under the snow, and their high jump to surprise and catch that animal — called “mousing” — is pretty spectacular. But even more spectacular is what we can’t see: the possible influence of magnetic alignment.
Jaroslav Červený and a large research team observed almost 600 mousing jumps by 84 foxes, and based on the data, they proposed that “…mousing red foxes may use the magnetic field as a ‘range finder’ or targeting system to measure distance to its prey…” From Ed Yong in 2011:
If they pounced to the north-east, they killed on 73% of their attacks; if they jumped in the opposite direction, they success rate stayed at 60%. In all other directions, only 18% of their pounces were successful…
Many animals have magnetoreception capabilities including birds, bats, mice, mole rats, fruit flies, honeybees, turtles, lobsters, sharks and stingrays.
If Červený is correct, then the red fox is unique in many ways. It would be the first animal known to use a magnetic sense to hunt, and the first to use magnetic fields to estimate distance rather than direction or position.
Sea Level! What is it and how do scientists calculate it? As it turns out, there are actually many complexities in determining this measurement. For example, Earth isn’t actually a sphere, gravity is stronger and weaker at different points around the globe, and of course, there are a lot of mountains that are no where near water — so how do we know what sea level would be? In this video, Minute Physics explains the details.
"It was the craftsmen who mastered the remarkable properties that go with specific materials. They were the first to journey towards the atom. The goldsmiths slowly refined their craft to take advantage of what gold alone could do…”