Weekly Space Hangout – November 15, 2013

Host: Fraser Cain

Guests: Jason Major & David Dickinson

Jason Major on:
Awesome New Image from Cassini
Mars Was Earthlike Millions of Years Ago

David Dickinson on:
Comet R1 LoveJoy at its brightest
Leonid Meteors this weekend
MAVEN Launches on Monday

Fraser Cain on:
Reminder re: Comet ISON photo contest
Cory Schmitz’ Aurora Photos
Curiosity’s Journey to Mount Sharpe
The Moon Has Bigger Craters on the Near Side
Super Typhoon Haiyan from Space
Two Workers Killed in Plesetsk

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.

Astronomy Cast 322: SOHO

As we’ve mentioned before, the Sun is a terrifying ball of plasma. It’s a good thing we’re keeping an eye on it. And that eye is the Solar and Heliospheric Observatory, or SOHO. Operating for more than 18 years now, SOHO has been making detailed observations of the Sun’s activity though an almost entire solar cycle. With so many years of operation, SOHO has some amazing stories to tell.

Continue reading “Astronomy Cast 322: SOHO”

Astronomy Cast 321: Solar Flares

Sometimes the Sun is quiet, and other times the Sun gets downright unruly. During the peak of its 11-year cycle, the surface of the Sun is littered with darker sunspots. And its from these sunspots that the Sun generates massive solar flares, which can spew radiation and material in our direction. What causes these flares, and how worried should we be about them in our modern age of fragile technology?
Continue reading “Astronomy Cast 321: Solar Flares”

What Would Happen if the Earth Stopped Turning?

What Would Happen if the Earth Stopped Turning?

This article was originally written in 2010, but we’ve now updated it and added this spiffy new video.

As you probably know, the Earth is rotating on its axis. This gives us day and night. Of course it’s impossible, but what would happen if the Earth stopped spinning? Remember, this isn’t possible, it can’t happen, so don’t worry.

Everything would be launched in a ballistic trajectory sideways
The first thing to think about is the momentum of everything on the surface of the Earth. You’re held down by gravity and you’re whizzing through space at a rotational velocity of 1,674.4 km/h (at the equator). You can’t feel it because of momentum. Just like how you can’t feel that you’re moving in a car going down the highway. But you feel the effects when you stop, or get into an accident. And so, if the Earth suddenly stopped spinning, everything on the surface of the Earth at the equator would suddenly be moving at more than 1,600 km/hour sideways. The escape velocity of Earth is about 40,000 km/hour, so that isn’t enough to fly off into space; but it would cause some horrible damage as everything flew in a ballistic trajectory sideways. Imagine the oceans sloshing sideways at 1,600 km/hour.

The rotational velocity of the Earth decreases as you head away from the equator, towards the poles. So as you got further away from the equator, your speed would decrease. If you were standing right on the north or south pole, you’d barely even feel it.

A day would last 365 days
The next problem is that day and night wouldn’t work the same any more. Right now the Earth is rotating on its axis, returning the Sun to the same position every 24 hours. But if the Earth stopped spinning, it would then take 365 days for the Sun to move through the sky and return to the same position. Half of the Earth would be baked for half a year, while the other hemisphere was in darkness. It would get very hot on the sunny side, and very cold in the shadowed side. You can imagine how that would be devastating to plants and animals. We get a hint of this at the poles, where you can experience weeks of permanent night and then weeks of permanent day. But imagine 6 months of night, followed by 6 months of day.

The Earth would become a perfect sphere
This might seem minor compared to the other catastrophes, but the Earth would become an almost perfect sphere. The Earth is currently rotating on its axis, completing one turn approximately every 24 hours. This rotational velocity causes the Earth to bulge out around its equator, turning our planet into an oblate spheroid (a flattened ball). Without this spin, gravity would be able to pull the Earth into a nice perfect sphere. This sounds interesting and probably harmless, but it’s actually a *big* problem. Because of the Earth’s bulge in the middle, the oceans are held out at the equator by 8 km. On perfect sphere Earth, the world’s oceans would redistribute, flooding many regions of the planet with an immense volume of water. We’d end up with a single continent around the middle of the planet, with oceans surrounding the north and south poles.

The Earth would no longer be tilted
The Earth’s tilt is defined by how the planet is rotating compared to the Sun. This axis of rotation defines the Earth’s seasons. But without any rotation, the concept doesn’t make sense any more. There’s still a north pole of the planet, where the radiation from the Sun is at its lowest angle, and an equator, where the light hits most directly. But there would no longer be seasons.

We have written many articles about the Earth for Universe Today. Here’s an article about why the Earth has seasons, and here’s an article about how the Earth protects us from space.

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

References:
NASA: Escape Velocity
NASA Ask Us: Earth and Moon
NASA: What would happen if the Earth stopped spinning?

Weekly Space Hangout – November 8, 2013

Host: Fraser Cain
Guests: Thad Szabo, Scott Lewis, Ian O’Neill, Alan Boyle, Nancy Atkinson, David Dickinson, Jason Major, Matthew Francis, Nicole Gugliucci

LINKS:
(Check out the comments for some more excellent discussion!)
Alan Boyle on Virgin Galactic
Nancy Atkinson on the hybrid solar eclipse
Jason Major on baby supermassive black holes
Ian O’Neill on quasars (BLACK HOLES DON’T SUCK)
Alan Boyle on Chelyabinsk
Security cam of Chelyabinsk
Matthew Francis on LUX
Nancy Atkinson on the sun (not literally)
Scott Lewis on Frontier Fields
Matthew Francis on Earth-density exoplanet
David Dickinson on GOCE
Kepler Orrery
Fireball FAQs

Astronomy Cast 320: Layers of the Sun

Our Sun isn’t just a terrifying ball of white hot plasma, it’s actually a lot more complex. It’s got layers. And today, we’re going to peel back those layers and learn about the Sun – from the inside out.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

Weekly Space Hangout – November 1, 2013: Comet ISON Special

We interrupt your regular Weekly Space Hangout for an hour-long special on Comet ISON, broadcast live from the Pacific Space Centre in Vancouver, BC.

We’ve got special guests +Pamela Gay, +Nicole Gugliucci, +David Dickinson and Sondy Springmann to discuss the upcoming arrival of Comet ISON.

We’ll discuss the history of the comet, review its orbit, and give you tips and tricks for how you can participate in this amazing event (or non-event).

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.