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FAQs

What’s the birthstone for March?

Photo credit:

Photo credit: Wikimedia

Happy birthday to all you March babies! March has two birthstones – aquamarine and bloodstone.

Are a star’s brightness and luminosity the same thing?

Image credit: NASA

Image credit: NASA

When we talk about the luminosity of a star, we are referring to the star’s intrinsic brightness. We are not talking about the star’s apparent magnitude – its brightness as it appears from Earth. For instance, most every star that you see with the unaided eye is larger and more luminous than our sun. The stars that we see at night are millions – even hundreds of millions – of times farther away than the sun. Regardless, you can still see these distant suns because many of them are hundreds or thousands of times more luminous than our local star.

What makes Venus the brightest planet?

Venus (brighter) and Mars (above) on February 15, 2015, submitted to EarthSky by Marsha Kircshbaum.  She got this shot as Point Reyes National Seashore in California.  Thank you, Marsha.

Venus (brighter) and Mars (above) on February 15, 2015, by Marsha Kircshbaum. She got this shot as Point Reyes National Seashore in California. Thank you, Marsha.

Venus is much brighter than any other planet viewed in Earth’s sky. It’s the third-brightest object in the sky, after the sun and moon. Click the links below to learn more about why Venus is so bright and when to see it as its brightest

How big are the biggest monster stars?

UY Scuti compared to our sun

UY Scuti compared to our sun. Image by Philip Park via Jillian Scudder

How big can stars get? And how do these monster stars get so big? When speaking of bigness among stars, you have to define your terms. The heaviest star is thought to be R136a1. It’s 265 times more massive than our sun – nearly twice as massive as what astronomers thought was possible. It’s the most massive star known at this time (February 2015). But there are more ways than one to measure stars’ bigness. In terms of sheer physical size, another exceedingly large star is UY Scuti. It’s only 30 times the sun’s mass, but has a radius more than 1,700 greater than the sun. Follow the links inside to learn more about these monster stars.

What are circumpolar stars?

482px-Circumpolar_AZ81

Circumpolar stars always reside above the horizon, and for that reason, never rise or set. All the stars at the Earth’s North and South Poles are circumpolar. Meanwhile, no star is circumpolar at the Earth’s equator. And in between?

What’s the birthstone for February?

Hey February babies! Happy birthday! Your birthstone, the amethyst, was the stone of royalty, representing power.

What do you know about the Yellowstone supervolcano?

Echinus Geyser, Yellowstone National Park. Image Credit: National Park Service.

Echinus Geyser, Yellowstone National Park. Image Credit: National Park Service.

Beneath Yellowstone National Park in the western United States, lies a hot, upwelling plume of mantle. Heat from the mantle melts the overlying rocks and the resulting magma pools close to Earth’s surface. Areas such as these are known as volcanic hotspots.

What causes the aurora borealis or northern lights?

Reisafjorden, Norway bathing in auroras on January 2, 2014.  Copyright 2014 Tor-Ivar Næss.

Reisafjorden, Norway bathing in auroras on. When charged particles from the sun strike atoms in Earth’s atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights. Image copyright 2014 Tor-Ivar Næss. Via WaitForIt on Facebook.

Don’t miss the photos at the bottom of this post!

How do snowflakes get their shape?

Photo by EarthSky Facebook friend Paula Lancaster Lupi of a snowflake and frost on her car window.

The shape of snowflakes is influenced by the temperature and humidity of the atmosphere.

What’s a safe distance between us and an exploding star?

Artist's illusration of a supernova via SmithsonianScience.org

Artist’s illustration of a supernova via SmithsonianScience.org

A supernova is a star explosion – destructive on a scale almost beyond human imagining. If our sun exploded as a supernova, the resulting shock wave probably wouldn’t destroy the whole Earth, but the side of Earth facing the sun would boil away. Clearly, the sun’s distance – 8 light-minutes away – isn’t safe. Fortunately, our sun isn’t the sort of star destined to explode as a supernova. But other stars, beyond our solar system, will. What is the closest safe distance? Follow the links inside to learn more.