Tides

Although tides are best appreciated from a comfortable beach chair, truly understanding the motion in the ocean requires a trip to the moon. As you may have noticed, the moon is Earth’s only natural satellite, locked in orbit by the Earth’s gravitational pull. But the moon has a gravitational pull of it’s own, which tugs on the planet’s oceans; the water on Earth’s moon-facing side – or sublunar point – bulges out slightly, while the water on the opposite side – or antipodal point – is pulled slightly “in,” towards the Earth’s core.

Stars

To kick off learnalittle's WEEK OF SPACE, we look to the stars.

A star is a massive, luminous ball of ionized gas (or plasma) that form in giant, slowly rotating clouds of dust called stellar nurseries. A cloud’s gravity gradually causes it to condense into a sphere; as it collapses, this ball becomes hotter and denser, eventually forming a protostar. Under incredibly high pressure, atoms that normally repel each other begin to collide and combine in a process called nuclear fusion. In the case of a new star, molecules of hydrogen collide to form helium. When the protostar’s heat and pressure hit 1 million °C, fusion begins and the star ignites.

Batteries

Make sure your laptop is fully charged, because today’s learnalittle is all about batteries.

A battery reacts two different kinds of metal to convert stored chemical energy into electricity through a series of ionic reactions. Batteries produce a strong, consistent current of electricity, ideal for powering electronic devices in a closed electrical circuit.

Dark Matter and Dark Energy

Space. As far as frontiers go, it’s pretty final – and even more mysterious. In this spirit, today’s post covers two of astrophysics’ most brain-boggling theories: dark matter and dark energy.

Our first mystery arose in 1933, when Swiss-born astrophysicist Fritz Zwicky attempted to estimate the total mass of a cluster of galaxies. But he encountered a problem. As background, the more mass an object has, the greater it’s gravitational pull – the force that attracts other objects. The greater an object’s gravitational pull, the faster objects rotating around it will move. Zwicky noticed that galaxies at the edge of the cluster were rotating way too fast for the mass he calculated; to account for speed, the cluster had to be about 400 times more massive.

Rainbows

Ditch the rose-colored glasses and prepare yourself for full-on Technicolor. Today on learnalittle, we’re chasing rainbows.

Rainbows appear when sunlight passes through moisture droplets in the atmosphere, producing a colorful ring – though only an arc is visible. When the sun is about 42° above the horizon (in the early morning or evening), droplets of moisture behave much like prisms: a ray of light refracts as it enters the droplet, reflects off the back, then refracts once more as it passes out of the droplet. This process disperses the ray into the colors of the visible spectrum of light.