Gather round the internets for another episode of the Weekly Space Hangout. Where our experienced team of journalists, astronomers and astronomer-journalists bring you up to speed on the big happenings in the universe of space and astronomy.
Our team this week:
Reporters: Casey Dreier, David Dickinson, Amy Shira Teitel, Sondy Springmann, Nicole Gugliuci
We record the Weekly Space Hangout every Friday at Noon Pacific, 3 pm Eastern. Join us live here on Universe Today, over on our YouTube account, or on Google+. Or you can watch the archive after the fact.
Did you know you can distinguish between stars and planets in the sky?
Stars twinkle, planets don’t.
Okay, that’s not actually correct. The stars, planets, even the Sun and Moon twinkle, all in varying amounts. Anything outside the atmosphere is going to twinkle.
If you’re feeling a little silly using the word twinkle over and over again, we can also use the scientific term: astronomical scintillation.
You can’t feel it, but you’re carrying the entire weight of the atmosphere on your shoulders. Every single square inch of your skin is getting pushed by 15 pounds of pressure. And even though astronomers need our atmosphere to survive, it still drives them crazy. As it makes objects in space so much harder to see.
Stars twinkle, I mean scintillate, because as light passes down through a volume of air, turbulence in the Earth’s atmosphere refracts light differently from moment to moment. From our perspective, the light from a star will appear in one location, then milliseconds later, it’ll be distorted to a different spot.
We see this as twinkling.
So why do stars appear to twinkle, while planets don’t?
Stars appear as a single point in the sky, because of the great distance between us and them. This single point can be highly affected by atmospheric turbulence. Planets, being much closer, appear as disks.
We can’t resolve them as disks with our eyes, but it still averages out as a more stable light in the sky.
Astronomers battle atmospheric turbulence in two ways:
First, they try to get above it. The Hubble Space Telescope is powerful because it’s outside the atmosphere. The mirror is actually a quarter the size of a large ground-based observatory, but without atmospheric distortion, Hubble can resolve galaxies billions of light-years away. The longer it looks, the more light it gathers.
Second, they try to compensate for it.
Some of the most sophisticated telescopes on Earth use adaptive optics, which distorts the mirror of the telescope many times a second to compensate for the turbulence in the atmosphere.
A beam from the Laser Star Guide on one of the VLT’s four Unit Telescopes helps to correct the blurring effect of Earth’s atmosphere before making observations (ESO/Y. Beletsky)Astronomers project a powerful laser into the sky, creating an artificial star within their viewing area. Since they know what the artificial star should look like, they distort the telescope’s mirror with pistons cancelling out the atmospheric distortion. While it’s not as good as actually launching a telescope into space, it’s much, much cheaper.
Now you know why stars twinkle, why planets don’t seem to twinkle as much, and how you can make all of them stop.
We have written many articles about stars here on Universe Today. Here’s an article that talks about a technique astronomers use to minimize the twinkle of the Earth’s atmosphere.
When tiny grains of dust impact our atmosphere, they leave a trail of glowing material, like a streak of light across the sky.
This is a meteor, or a shooting star.
On any night, you can go outside, watch the sky, and be guaranteed to see one. Individual meteors start as meteoroids – pieces of rock smaller than a pebble flying around the Solar System.
Even though they’re tiny, these objects can be moving at tens of thousands of kilometers per hour. When they hit Earth’s atmosphere, they release tremendous amounts of energy, burning up above an altitude of 50 kilometers.
As they disintegrate, they leave a trail of superheated gas and rocky sparks which last for a moment in the sky, and then cool down and disappear from view.
Throughout the year there are several meteor showers, when the number of meteors streaking through the sky increases dramatically. This happens when the Earth passes through the trail of dust left by a comet or asteroid.
Meteor showers are when night sky puts on a special show, and it’s a time to gather your friends and family together and enjoy the spectacle.
Some showers produce only a trickle of objects, while others, like the famous Perseid meteor shower, can dependably bring dozens of meteors each hour.
Meteor Burst – Credit: NASAIf the trail is dense enough, we can get what is called a meteor storm. The most powerful meteor storms in history truly made it look like the sky was falling. The Leonids in 1833 produced hundreds of thousands per hour.
Meteor showers take their name from the constellation from where they appear to originate. For example, the Perseids trace a trail back to the constellation Perseus; although you can see them anywhere across the sky.
You can see meteors any time of the year, and you don’t need any special equipment to enjoy an average meteor shower. But here are some ways you can improve your experience.
You’ll want to find a location with as clear a view to the horizon in as many directions as possible. An open field is great. Lie on your back, or on a reclining chair, look up to the sky
… and be patient.
A bright fireball meteor in twilight. The Lyrids, like all meteor showers, offer up the occasional fireball among a mix of fainter meteors. Credit: John ChumackYou probably won’t see a meteor right away, but after a few minutes, you should see your first one.
The longer you look, the more you’ll see, and the better chance you’ll have of seeing a bolide or fireball; a very bright meteor that streaks across the sky, leaving a trail that can last for a long time.
You can see meteors any time that it’s dark, but the most impressive ones happen in the early morning, when your location on Earth is ploughing directly into the space dust.
You also want the darkest skies you can get, far away from city light pollution, and many hours after the Sun has gone down.
Enjoy the early evening meteors, but then set your alarm and get up around 4 in the morning to see the real sky show.
The radiant for the Persieds, looking to the NE from latitide ~30N at around 2AM local. Created by the Author in Starry Night).If I could only see one meteor shower every year, it would have to be the Perseids. These come when the Earth passes through the tail of Comet Swift-Tuttle, and peak around August 12th every year. It’s not always the most active shower, but it’s warm outside in the Northern hemisphere, and this is a fun activity to do with your friends and family.
It’s Sunday night, and that means it’s time for another Virtual Star Party. This week we had an action-packed episode, with a full house of astronomers. Thanks to relatively clear skies across North America, we had 7 telescopes broadcasting the night sky.
We were also joined by Kevin Nelson, the Vice President of Sales and Marketing for Quantum Scientific Imaging. This is the company that makes high-end CCD cameras that many of our astronomers use. Kevin stuck around for the entire show, showed off a few cameras and answered questions from both inside and outside the Hangout.
We were also joined by a new astronomer, Darryl Van Graal, who was taking wide-field shots of the Ontario skies, hoping for a meteor or an aurora. No luck. 🙁
There were just too many images seen to even provide a partial list. We saw the Ring Nebula, Dumbbell Nebula, Cocoon, Lagoon, Triffid, Eagle, star clusters, galaxies… and so much more.
We gather together every Sunday night on Google+ when it get dark on the West Coast to hold the Virtual Star Party. If you’d like a notification for when it’s happening, make sure you subscribe to the Universe Today channel on YouTube.
Charlie McDonnell is a phenomenally successful YouTube blogger, with more than 2 million subscribers. And from time to time he likes to wrap his head around complicated topics in space and astronomy.
In this short video, Charlie tackles the implications of what it means to live in an infinite Universe. If the Universe is truly infinite, and there are a finite number of ways that matter can be configured, then if you travel far enough, you will run into duplicates. Continue reading “Are There an Infinite Number of Charlies?”
It’s time for another Weekly Space Hangout, where we give you a rundown of the big space news stories of the week, from a team of scientists and space journalists.
We record the Weekly Space Hangout live on Google+ every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch the show live here on Universe Today, or the archived version on YouTube.
An idea that really captures my imagination is what kinds of future civilizations there might be. And I’m not the only one. In 1964, the Soviet astronomer Nikolai Kardashev defined the future of civilizations based on the amount of energy they might consume.
A Type I civilization would use the power of their entire planet. Type II, a star system, and a Type III would harness the energy of an entire galaxy. It boggles the mind to think about the engineering required to rearrange the stars of an entire galaxy.
Is it possible to move a star? Could we move the Sun?
This idea was first proposed by physicist Dr. Leonid Shkadov in his 1987 paper, “Possibility of controlling solar system motion in the galaxy”.
Here’s how it works.
A future alien civilization would construct a gigantic reflective structure on one side of their star. Light from the star would strike this structure and bounce off, pushing it away.
If this reflective structure had enough mass, it would also attract the star with its gravity.
The star would be trying to push the structure away, but the structure would be pulling the star along with it.
If a future civilization could get this in perfect balance, it would be able to “pull” the star around in the galaxy, using its own starlight as thrust. At first, you wouldn’t get a lot of speed. But by directing half the energy of a star, you could get it moving through the galaxy.
Over the course of a million years, you would have changed its velocity by about 20 meters/second. The star would have traveled about 0.3 light years, less than 10% of the way to Alpha Centauri. Keep it up for a billion years and you would be moving a thousand times faster. Allowing you to travel 34,000 light years, a significant portion of the galaxy.
Imagine a future civilization using this technique to move their stars to better locations, or even rearranging huge portions of a galaxy for their own energy purposes.
This may sound theoretical, but Duncan Forgan, from the University of Edinburgh suggests a practical way to search for aliens moving their stars. According to him, you could use planet-hunting telescopes like Kepler to detect the bizarre light signatures we’d see from a Shkadov Thruster. There’s nothing in the laws of physics that says it can’t happen.
It’s fun to think about, and gives us another way that we could search for alien civilizations out there across the galaxy.
The idea that there is life on other worlds is humbling and exciting, and finding life on another world would change everything. This has been a driving force for scientists for decades. We find life wherever we find water on Earth, in pools of boiling water, inside glaciers, even in nuclear reactors.
Because of this, our best candidate for life is probably Mars.
The planet is hostile to life now, but evidence is mounting that it was once a warm and habitable world, with rivers, lakes and oceans. Mars could have vast reserves of subsurface water, where life could thrive even now.
If we did discover life there, it’s possible that it’s completely unrelated to Earth life. This would demonstrate that life can originate on almost any world, with the right conditions.
It’s also possible that life on Mars is related to Earth, and our two planets share a common ancestor billions of years in the past.
This is a theory called panspermia.
It suggests that life on Earth and Mars are connected. That life has been traveling from Mars to Earth and vice-versa for billions of years. “How is this possible?” you might ask.
Meteorites.
Mars Meteorite. Credit: NASAWe know that both Earth and Mars have been hammered by countless asteroids in their history long. Some of these impacts are so powerful, rock debris is ejected into escape orbits. This blasted rock could orbit the Sun for eons and then re-enter the atmosphere of another planet.
We know this is true, because we have meteorites on Earth which originated on Mars. Tiny gaps in the rock contained gases which match the atmosphere of Mars. You would think that an asteroid strike would sterilize life in the rocks, but amazingly, bacterial life can survive this process.
Microbial life can even withstand the harsh temperature, radiation and vacuum of space for thousands – possibly millions of years – riding inside their rocky spacecraft.
Some bacteria could even survive when their “space rock” enters the atmosphere of another world.
So a natural space exploration program has been in place for billions of years, with asteroid strikes hurling life-filled rocks into space, which then smash into other worlds.
Life on Mars has been elusive so far, but there are missions in the works which will have the scientific instruments on board to hunt for life on the Red Planet.
Artist illustration of a Europa probe. Image credit: NASA/JPLIf we do find it, will we discover that it’s actually related to us? If we find life under the ice on Europa, or in the cloud tops of Venus, will we discover the same thing?
It gets even stranger.
The Solar System is leaving a trail of debris behind as it orbits around the Milky Way, which could be colliding with other star systems. Which means, it’s possible that life around other stars is related to us too.
So maybe there’s no life on Mars, or if there is, maybe it originated on its own, or maybe it’s all related, as a result of trading life back and forth across giant spans of time and space.
Whatever the case, the search sure is going to be exciting.
In case you missed it live, here was our Virtual Star Party for Sunday, July 28, 2013. We had two active telescopes going, but they were highly automated scopes slewing from target to target with precise efficiency. We probably hit a new record this week, with the number of objects we targeted. We had nebulae, galaxies, star clusters and special appearances from Neptune… and Pluto; our first of the season!
We get together every Sunday night for a Virtual Star Party in a live Google+ Hangout on Air. You can watch live, and ask your questions about astronomy and astrophotography; we’ll even take requests.
We’ll broadcast the video live from here on Universe Today, or over on Google+.
If you’re an astronomer and have the ability to view images from your telescope on your computer, we’d love to have you join us some week. Especially if you live in Europe or South America.
Trying to explain the topology of the Universe is really complicated… for humans. But it clearly comes naturally to Zogg the Alien from Betelgeuse. In this 10-minute video, the plucky alien vividly describes how we could have a Universe which is flat and finite, but doesn’t have an edge. How we could travel in one direction and return to our starting point, never bumping into the outside of the Universe.
What is the Universe expanding into? Nothing, it’s just expanding.
Dig a little further through Zogg’s YouTube channel, and you’ll see a great collection of explainers on eating, vision; and even esoteric topics like imagination and beauty.
I’d love to see more in this series Zogg… hint, hint.
