Space and astronomy news
Host: Fraser Cain (@fcain)
Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Brian Koberlein (@briankoberlein)
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Continue reading “Weekly Space Hangout – Nov. 7, 2014: Ship Updates & Solar System Formation”
Host: Fraser Cain (@fcain)
Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)
Alessondra Springmann (@sondy)
Ken Kremer (kenkremer.com / @ken_kremer)
Continue reading “Weekly Space Hangout – Oct. 31, 2014: Bad Week in Space”
Halloween is just around the corner. And in what appears to be an act of cosmic convergence, Hubble captured a spooky image of Jupiter staring back at us with a cyclops eye!
While this is merely a convenient illusion caused by the passage of Ganymede in front of Jupiter – something it does on a regular basis – the timing and appearance are perfect.
Continue reading “Just In Time for Halloween: Jupiter Gets a Giant Cyclops Eye!”
I ran into this intriguing infographic over on Reddit that claimed that you could fit all the planets of the Solar System within the average distance between the Earth and the Moon.
I’d honestly never heard this stat before, and it’s pretty amazing how well they tightly fit together.
But I thought it would be a good idea to doublecheck the math, just to be absolutely certain. I pulled my numbers from NASA’s Solar System Fact Sheets, and they’re a little different from the original infographic, but close enough that the comparison is still valid.
| Planet | Average Diameter (km) |
| Mercury | 4,879 |
| Venus | 12,104 |
| Mars | 6,771 |
| Jupiter | 139,822 |
| Saturn | 116,464 |
| Uranus | 50,724 |
| Neptune | 49,244 |
| Total | 380,008 |
The average distance from the Earth to the Moon is 384,400 km. And check it out, that leaves us with 4,392 km to spare.
So what could we do with the rest of that distance? Well, we could obviously fit Pluto into that slot. It’s around 2,300 km across. Which leaves us about 2,092 km to play with. We could fit one more dwarf planet in there (not Eris though, too big).
The amazing Wolfram-Alpha can make this calculation for you automatically: total diameter of the planets. Although, this includes the diameter of Earth too.
A nod to CapnTrip on Reddit for posting this.
Host: Fraser Cain (@fcain)
Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Continue reading “Weekly Space Hangout – Oct. 17, 2014: Comet Siding Spring & Dark Matter”
Prolific astrophotographer Joseph Brimacombe from Australia shot this beauty from his Savannah Skies Observatory near Cairns. He notes on Flickr that “Jupiter has been enhanced for effect,” but what a lovely effect! Plus what a great view of the landscape in Queensland.
Taken with a Canon 5D Mk II and 28-300 mm lens, six frames; three exposures each.
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The closest planetary conjunction of the year graced the skies this morning, and astrophotographers were out in force to marvel at the beauty. The duo were just 11.9’ apart, less than half the diameter of a Full Moon. Also joining the view was M44, the Beehive Cluster. We start with this gorgeous shot from Queensland, Australia by one of our longtime favorite astrophotographers, Joseph Brimacombe.
But wait… there’s more! Much more! See below:
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Jupiter is like a jawbreaker. Dig down beneath the swirling clouds and you’ll pass through layer after layer of exotic forms of hydrogen. What’s down there, deep within Jupiter?
What’s inside Jupiter? Is it chameleons? Candy? Cake? Cheddar? Chemtrails? No one knows. No one can ever know.
Well, that’s not entirely true… or even remotely true. Jupiter is the largest planet in the Solar System and two and a half times the mass of the other planets combined. It’s a gas giant, like Saturn, Uranus, and Neptune. It’s almost 90% hydrogen and 10% helium, and then other trace materials, like methane, ammonia, water and some other stuff. What would be a gas on Earth behaves in very strange ways under Jupiter’s massive pressure and temperatures.
So what’s deep down inside Jupiter? What are the various layers and levels, and can I keep thinking of it like a jawbreaker? At the very center of Jupiter is its dense core. Astronomers aren’t sure if there’s a rocky region deep down inside. It’s actually possible that there’s twelve to forty five Earth masses of rocky material within the planet’s core. Now this could be rock, or hydrogen and helium under such enormous forces that it just acts that way. But you couldn’t stand on it. The temperatures are 35,000 degrees C. The pressures are incomprehensible.
Surrounding the core is a vast region made up of hydrogen. But it’s not a gas. The pressure and temperature transforms the hydrogen into an exotic form of liquid metallic hydrogen, similar to the liquid mercury you’d see in a thermometer. This metallic hydrogen region turns inside the planet, and acts like an electric dynamo. Similar to our planet’s own iron core, this gives the planet a powerful magnetic field.
The next level up is still liquid hydrogen, but the pressure’s lower, so it’s not metallic any more. And then above this is the planet’s atmosphere. The upper layers of Jupiter’s atmosphere is the only part we can see. Those bands on the planet are clouds of ammonia that rotate around the planet in alternating directions. The lighter color zones are colder ammonia ice upwelling from below. Here’s the exciting part. Astronomers aren’t sure what the darker regions are.
Still think you want to descend into Jupiter, to try and walk on its rocky interior? NASA tried that. In order to protect Jupiter’s moons from contamination, NASA decided to crash the Galileo spacecraft into the planet at the end of its mission. It only got point two percent of the way down through Jupiter’s radius before it was completely destroyed.
Jupiter is a remarkably different world from our own. With all that gravity, normally lightweight hydrogen behaves in completely exotic ways. Hopefully in the future we’ll learn more about this amazing planet we share our Solar System with.
What do you think? Is there a rocky core deep down inside Jupiter?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Eureka – it’s Europa! And a brand-new image of it, too! (Well, kinda sorta.)
The picture above, showing the icy moon’s creased and cracked surface, was made from images acquired by NASA’s Galileo spacecraft during its exploration of Jupiter and its family of moons in 1997 and 1998. While the data itself isn’t new per se the view seen here has never been released by JPL, and so it’s new to you! (And to me too.)
The original high-resolution images were acquired on Nov. 6, 1997, in greyscale and colorized with data acquired during a later pass by Galileo in 1998. The whiter areas are regions of relatively pure water ice, while the rusty red bands are where ice has mixed with salts and organic compounds that have oozed up from deeper within Europa.
Read more: Hydrogen Peroxide Could Feed Life on Europa
The entire image area measures about 101 by 103 miles across (163 km x 167 km).
Europa has long been one of the few places we know of outside our own planet where life could very well have evolved and potentially still exist. Getting a peek below the icy moon’s frozen crust — or even a taste of the recently-discovered water vapor spraying from its south pole — is all we’d need to further narrow down the chances that somewhere, something could be thriving in Europa’s subsurface seas. Get a planetary scientist’s perspective in a video interview with Dr. Mike Brown here.
Launched in October 1989, the Galileo spacecraft arrived at Jupiter in December 1995. Through primary and extended missions Galileo explored the giant planet and its family of moons until plunging into Jupiter’s atmosphere on September 21, 2003. Learn more about Galileo here, and check out some of the amazing images it acquired on the CICLOPS imaging diary page here.
Source: NASA’s Planetary Photojournal
Have you ever noticed that everything in space is a sphere? The Sun, the Earth, the Moon and the other planets and their moons… all spheres. Except for the stuff which isn’t spheres. What’s going on?
Have you noticed that a good portion of things in space are shaped like a sphere? Stars, planets, and moons are all spherical.
Why? It all comes down to gravity. All the atoms in an object pull towards a common center of gravity, and they’re resisted outwards by whatever force is holding them apart. The final result could be a sphere… but not always, as we’re about to learn.
Consider a glass of water. If you could see the individual molecules jostling around, you’d see them trying to fit in as snugly as they can, tension making the top of the water smooth and even.
Imagine a planet made entirely of water. If there were no winds, it would be perfectly smooth. The water molecules on the north pole are pulling towards the molecules on the south pole. The ones on the left are pulling towards the right. With all points pulling towards the center of the mass you would get a perfect sphere.
Gravity and surface tension pull it in, and molecular forces are pushing it outward. If you could hold this massive water droplet in an environment where it would remain undisturbed, eventually the water would reach a perfect balance. This is known as “hydrostatic equilibrium”.
Stars, planets and moons can be made of gas, ice or rock. Get enough mass in one area, and it’s going to pull all that stuff into a roughly spherical shape. Less massive objects, such as asteroids, comets, and smaller moons have less gravity, so they may not pull into perfect spheres.
As you know, most of the celestial bodies we’ve mentioned rotate on an axis, and guess what, those ones aren’t actually spheres either. The rapid rotation flattens out the middle, and makes them wider across the equator than from pole to pole. Earth is perfect example of this, and we call its shape an oblate spheroid.
Jupiter is even more flattened because it spins more rapidly. A day on Jupiter is a short 9.9 hours long. Which leaves it a distorted imperfect sphere at 71,500 km across the equator and just 66,900 from pole to pole.
Stars are similar. Our Sun rotates slowly, so it’s almost a perfect sphere, but there are stars out there that spin very, very quickly. VFTS 102, a giant star in the Tarantula nebula is spinning 100 times faster than the Sun. Any faster and it would tear itself apart from centripetal forces.
This oblate spheroid shape helps indicate why there are lots of flattened disks out there. This rapid spinning, where centripetal forces overcome gravitational attraction that creates this shape. You can see it in black hole accretion disks, solar systems, and galaxies.
Objects tend to form into spheres. If they’re massive enough, they’ll overcome the forces preventing it. But… if they’re spinning rapidly enough, they’ll flatten out all the way into disks.