Universe Today

Question: How far away are the planets?

Answer: To answer this question, we'll consider the distance from each of the planets to the Sun. Before we start though, there's a term in astronomy that you'll want to remember: astronomical unit. One astronomical unit (or AU) is the distance from the Earth to the Sun.

You should also note that all of the planets orbit the Sun in ellipses. This means that their distance to the Sun varies depending on what point they are in their orbits. Astronomers call the closest point perihelion, and the most distant point aphelion.

As a special bonus, I'll also let you know the closest point that each of the planets gets to Earth.

Mercury
Closest: 46 million km (.307 AU)
Furthest: 70 million km (.466 AU)
Average: 57 million km (.387 AU)

Closest to Mercury from Earth: 77.3 million km

Here are some Mercury interesting facts.

Venus
Closest: 107 million km (.718 AU)
Furthest: 109 million km (.728 AU)
Average: 108 million km (.722 AU)

Closest to Venus from Earth: 40 million km

Mars
Closest: 205 million km (1.38 AU)
Furthest: 249 million km (1.66 AU)
Average: 228 million km (1.52 AU)

Closest to Mars from Earth: 65 million km

Jupiter
Closest: 741 million km (4.95 AU)
Furthest: 817 million km (5.46 AU)
Average: 779 million km (5.20 AU)

Closest to Jupiter from Earth: 588 million km

Saturn
Closest: 1.35 billion km (9.05 AU)
Furthest: 1.51 billion km (10.12 AU)
Average: 1.43 billion km (9.58 AU)

Closest to Saturn from Earth: 2.57 billion km

Uranus
Closest: 2.75 billion km (18.4 AU)
Furthest: 3.00 billion km (20.1 AU)
Average: 2.88 billion km (19.2 AU)

Closest to Uranus from Earth: 2.57 billion km

Neptune
Closest: 4.45 billion km (29.8 AU)
Furthest: 4.55 billion km (30.4 AU)
Average: 4.50 billion km (30.1 AU)

Closest to Neptune from Earth: 4.3 billion km

As a special bonus, we'll include Pluto too, even though Pluto is not a planet anymore.

Pluto
Closest: 4.44 billion km (29.7 AU)
Furthest: 7.38 billion km (49.3 AU)
Average: 5.91 billion km (39.5 AU)

Closest to Pluto from Earth: 4.28 billion km

Filed under: Questions | 7 Comments »

Question: What is the closest star?

Answer: The Sun.

That was an easy one… next question?

Okay, fine, it was a trick question, I know. Let's see if we can come up with the actual answer to the question, "except for the Sun, what is the closest star?"

The closest star system that we know of is Alpha Centauri, located about 4.37 light years away (41.5 trillion km). The system easy to see with the unaided eye - if you live in the Southern hemisphere. In fact, Alpha Centauri is the 4th brightest star in the star in the sky.

But there's a catch. Alpha Centauri is actually made up of three stars orbiting one another. They're too bright to be seen as separate stars without a telescope. But with a telescope, it's possible to split the star into two. These are Alpha Centuari A and B.

So which one's closer? Neither.

The Alpha Centauri system has a third, much dimmer star called Proxima Centauri. While Alpha Centauri A and B are 4.37 light-years away, The red dwarf Proxima Centauri is located a mere 4.22 light-years away. If humans ever reach out to launch spacecraft to another world, Proxima Centauri would be their likely destination.

Alpha Centauri orbit one another, getting as close as 11.2 astronomical units (the distance from the Sun to Saturn), while Proxima Centauri is about 13,000 astronomical units away. Most astronomers think that Proxima Centauri orbits the binary pair, but there are some who think it's just passing by, and not actually part of the system.

Here's a list of the 10 closest stars, with their distance in light-years:
Proxima Centauri - 4.22
Alpha Centauri A - 4.37
Alpha Centauri B - 4.37
Barnard's Star - 5.96
Wolf 359 - 7.78
Sirius A - 8.58
Sirius B- 8.58
Luyten-8 A - 8.73
Luyten-8 B - 8.73
Ross 154 - 9.68

Filed under: Astronomy, Questions | 1 Comment »

The ionosphere is the final layer of atmosphere before space. This highly dynamic region is constantly exposed to the full intensity of the Sun, harsh ultraviolet radiation breaking down molecules and atoms. Highly charged ions and free electrons therefore fill the ionospheric layers. Critical to terrestrial communications, the ionosphere also plays host to the largest lightshow on Earth, the Aurora. Now NASA-funded research has developed a live "4D Ionosphere" plugin for Google Earth. Now you can fly through the atmosphere's uppermost reaches without even leaving your desk…
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Filed under: Earth, Earth Observation | 9 Comments »

Can a planet like Earth be considered a single living organism? After all, the human body is composed of hundreds of billions of bacteria, and yet we consider the human body to be a single organism. The Gaia Hypothesis (or popularly known as "Gaia Theory") goes beyond the individual organisms living on Earth, it encompasses all the living and non-living components of Earth's biosphere and proposes that the complex interacting systems regulate the environment to a very high degree. So much so, that the planet may be viewed as a single organism in its own right. What's more this hypothesis was developed by a NASA scientist who was looking for life on Mars…
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Filed under: Earth | 55 Comments »

Steve Squyres and the Mars Exploration Rover team knew from the beginning that dust could cause a problem for the rovers, Spirit and Opportunity. When a thick layer of dust coats the solar panels, it blocks the sunlight that generates power for the six-wheeled robots. In the summer of 2007 a huge dust storm blanketed Mars, and deposited a fair amount of dust on solar panels of both rovers. Spirit, especially accumulated a lot of dust on its solar array. Currently, only about one-third of incoming sunlight is able to penetrate dust on Spirit’s solar panels to be converted to electricity. As a result, Spirit is experiencing the lowest energy levels to date and accumulating a backlog of data waiting to be transmitted to Earth. If only a dust devil would come along…
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Filed under: Mars, Missions | 22 Comments »

It’s fairly certain that the Mars Polar Lander and the Beagle lander crash landed on Mars, never to be heard from again. Well, what if crash landing was no problem? What if a robotic spacecraft could just reassemble and fix itself if there was a mishap on the way to another planet’s surface? That type of science fiction is getting closer to reality. A group of researchers from the University of Pennsylvania have developed a robot made of separate modules that can recognize each other and reassemble itself if they crash or get kicked apart. Maybe this could solve the problems of landing on Mars!
Except we haven't figured out how to reassemble people, yet.

Take a look a the video. It's pretty remarkable, although I have to admit, I had visions of the Terminator after watching it….

Original News Source: New Scientist

Filed under: Uncategorized | 11 Comments »

The past couple of weeks we've had a 'mystery' image, and asked our readers to guess what world in our solar system was featured in the image. Most everyone seemed to enjoy it, and it was fairly popular, so we've decided to make it a regular feature. I was going to call it the 'Wednesday Where in the World (and What World) Is This?' but that's just too long, not to mention too many W's in one headline. So to brief it up, and since this is "Universe Today," we've decided to call it "Where In The Universe?" Look for it every Wednesday.

Above is this week's mystery image. If you keep an eye on the images being released by the various spacecraft traveling our solar system, you may have seen this one before. Remember, you have 8 planets, 169 known moons, a handful of dwarf planets and lots of asteroids in our solar system to choose from. Don't cheat — make your guess before you click to continue…
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Filed under: Where In the Universe? | 20 Comments »

Cape Canaveral's Titan launch pad gantry was demolished on Sunday. The tower was built in the 1990's to support the US Air Force Titan 4 rocket program. The site has been used for NASA missions as well, including the launch of the Cassini-Huygens Saturn mission in 1997. Launch Complex 40 is being demolished and then refurbished to make way for the new SpaceX Falcon rocket launch facility. Now the gantry is rubble, the clean up operation can begin…
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Filed under: Space Flight | 10 Comments »

Cassini scientists know for sure their spacecraft isn’t in Kansas anymore. Cassini’s been keeping an eye on a powerful electrical storm that’s been raging on Saturn for five months now, with lightning bolts 10,000 times more powerful than those found on Earth. But Cassini has also been busy flying by moons like Enceladus and Titan during this time, and therefore can’t constantly watch the storm. So amateur astronomers have been assisting the Cassini science team by monitoring this tempest in the “Storm Alley” region of Saturn. It’s no Great Red Spot, but it's the longest lasting electrical storm ever detected in our solar system.
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For the first time, the most extreme collision to occur in the cosmos has been observed. Galaxies are known to hide supermassive black holes in their cores, and should the galaxies collide, tidal forces will cause massive disruption to the stars orbiting around the galactic cores. If the cores are massive enough, the supermassive black holes may become trapped in gravitational attraction. Do the black holes merge to form a super-supermassive black hole? Do the two supermassive black holes spin, recoil and then blast away from each other? Well, it would seem both are possible, but astronomers now have observational evidence of a black hole being blasted away from its parent galaxy after colliding with a larger cousin.
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Filed under: Black Holes | 12 Comments »

Question: Why Does Jupiter Have a Red Spot?

Answer: Jupiter is beautiful to look at, both in a backyard telescope and with the Hubble Space Telescope. Even in the smallest telescope you can see atmospheric bands across the planet, and its 4 largest moons orbiting around it. With larger telescopes you can see the famous Great Red Spot - a swirling storm larger than the Earth.

Astronomers have been observing the Great Red Spot for more than 300 years, so it's incredibly long lasting. But it is changing. In 2004, the Great Red Spot was only half the size it was a century earlier, reaching a total size of 40,000 km. At this current rate, astronomers think it will become circular by 2040.

Thanks to recent missions to Jupiter, like Galileo, Cassini and New Horizons, scientists are learning a tremendous amount about how the atmosphere on Jupiter works.

Hot gases in Jupiter's atmosphere are constantly swirling around, rising and falling. As cooler gas falls down through the atmosphere, the Coriolis force causes the region to start swirling. These eddies can last for a long time because there is no solid ground on Jupiter to create friction.

These eddies can move around and merge into one another, creating larger and larger storms, which last for longer periods. According to theories, several of these larger storms came together, combining their energy to create the long lived Great Red Spot.

We can see this process happening again with another spot on Jupiter called Oval BA. It was first discovered a few years ago when three white storms merged together. This new "Red Spot Jr." has been stable in the atmosphere of Jupiter for more than 6 years now. It and the larger Red Spot have even passed each other several times now, and not caused much damage.

Scientists think the Great Red Spot has its characteristic red color because the strength of the storm is digging down into Jupiter's atmosphere, bringing complex organic molecules to the high atmosphere.

Filed under: Jupiter, Questions | No Comments »

I signed up for Twitter a couple of years ago, but I never got around to actually using it. Some part of my brain thinks it would be a great way to do… something. But I have no idea what that would be. I'll need you to teach me, and help me understand what you'd like to see from my Twitter feed.

Obviously, you don't want to hear about the minutia of my life, but I think there's value in great big collaborative conversations. Part of me finds it very exciting, and part of me thinks it's a time sucking black hole. What am I missing?

Here's my Twitter feed.

Filed under: Blog | 12 Comments »

It appears the Earth's climate has the ability to naturally regulate atmospheric carbon dioxide levels. Historic records extracted from ice cores show quantities of CO₂ have varied widely in the last hundreds of thousands of years. This evidence appears to support the global warming critics view that current observations of the human-induced greenhouse effect is actually naturally occurring and the effects of carbon on the climate is over-hyped. However, a new study shows that although carbon dioxide levels may have been larger in the past, the Earth's natural processes had time to react and counteract global warming. The current trend of industrial emissions has been far more accelerated than any historic natural process, natural climate "feedback loops" cannot catch up to remove CO₂ from the atmosphere.
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Filed under: Environment | 52 Comments »

Astronomers looking at galaxies in the universe’s distant past were surprised to find some compact, very young galaxies that have masses similar to a mature, grown-up galaxy. Using the Hubble Space Telescope, astronomers discovered nine small galaxies, each weighing in at 200 billion times the mass of the Sun. The galaxies, each only 5,000 light-years across, are a fraction of the size of today's adult galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.
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Filed under: Hubble | 5 Comments »

Question: Why Can't We Launch our Trash Into Space?

Answer: Now wouldn't that be a tidy solution to a big problem? Gather together all the garbage, bundle it up and fire it off into space. Maybe just dump it into the Sun. We could live in a world without trash.

There are just two problems: humans produce an enormous amount of garbage; and rocket launches are extremely expensive.

It's been estimated that launching material on the space shuttle costs about $10,000/pound ($22,000/kg). Even if engineers could bring down prices by a factor of 10, it would still be thousands of dollars to launch the garbage into space. Let's imagine a wonderful dream world, where launch costs could be brought down to $1,000/kg - a factor of 1/20th the cost to launch on the space shuttle.

It has also been estimated that the United States alone produces 208 million metric tonnes of garbage per day… per day! So, to launch all that trash into space would cost the United States $208 trillion per day… per day!

The gross domestic product of the United States was $13.13 trillion in 2006, which works out to be about $36 billion a day. In other words, the United States would need to spend 5,800 times its daily gross domestic budget, just to launch its trash into space.

What about nuclear waste? A nuclear reactor releases about 25-30 tonnes of spent fuel every year. With our dream budget of $1,000/kg, that would cost about $25 million to launch a single reactor's waste into orbit. According to Wikipedia, there are 63 operating reactors in the US, so it would cost about $1.6 billion/year to dispose of the nuclear waste generated.

It's been estimated that Yucca Mountain - the United State's current plan to store nuclear waste - will cost about $58 billion to store waste over the course of 100 years. So storing waste in Yucca Mountain will cost about 1/3rd the price of launching that material into space. Not to mention the terrible risk of launching rockets full of nuclear waste into space - imagine what might happen if a rocket exploded in mid-flight…

I'm sure I've made some math errors here somewhere…

Filed under: Questions, Space Flight | 14 Comments »

Where you want to go depends on where you are. And if you've got a GPS system in your hands, and the most accurate clock ever sent into space overhead, you'll always know exactly where you are. ESA's GIOVE-B satellite blasted into space on Sunday, taking the next step for the deployment of a European satellite navigation system.
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Filed under: Satellites | 1 Comment »

The folks over at Ars Technica report that the Japanese Space Agency, JAXA, announced they are now accepting proposals for a microprobe that can hitch a ride with the Venus Climate Orbiter, Japan's upcoming robotic mission to Venus. They will provide a free ride to either a low-Earth orbit or on a trajectory toward Venus. There are just a few requirements that JAXA has specified:
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Filed under: Venus | 7 Comments »

India’s space agency sent a record 10 satellites into Earth orbit with a single launch early Monday. The Polar Satellite Launch Vehicle (PSLV) rocket ejected all the satellites within minutes of each other after liftoff from the Sriharikota space station in southern India. Initial signals indicated all the satellites were working normally. India is seeking to compete with other space-faring nations for commercial launch services, and this mission's success demonstrates India's ability to launch multiple payloads into precise orbit. The flight breaks the previous record of eight satellites launched at once by a Russian rocket, according to Indian news reports.

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Filed under: Missions | 9 Comments »

Some of the oldest structures in the Milky Way are the globular clusters. Ancient collections of millions of stars, that have held together by mutual gravity over billions of years. But new data collected by NASA's Chandra X-Ray Observatory casts doubt on their "ancient nature". They might be surprisingly less mature than astronomers previously believed.
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Filed under: Astronomy | 13 Comments »

Good mystery novels keep you in suspense to the very end. Luckily, our universe does the same to us. While we learn more, we learn that we have so much more to go. Helen Quinn and Yossi Nir in their book The Mystery of the Missing Antimatter look at one outstanding puzzle of particle physics. Suspense may lack somewhat but there's no doubting that some high powered intellects are exercising lots of gray matter.
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Filed under: Book Reviews | 2 Comments »

This is a show we wanted to do since we started Astronomy Cast but we always thought it was too early. We wanted you to know that we're positive, happy people with enthusiasm for astronomy and the future. It's time for some sadness. It's time for a grim look to see what the future holds for the Universe. This week we stay close to home and consider the end of humanity, the Earth, the Sun, and the entire Solar System. Next week we'll extend out to the very end of the Universe.

Click here to download the episode

The End of the Universe Part 1: The End of the Solar System - Show notes and transcript

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

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You only have to walk outside at night, look up and not see the Milky Way to know that light pollution is a problem. And seen from space at night, the Earth's surface glows with the light of millions of homes, buildings, cars and streetlights. Seen at night, our impact on the Earth is immediate and obvious.

A few years ago, NASA and NOAA compiled a complete world map of the nighttime Earth, using 9 months of data collected by satellites. This "Night Lights" image is pretty famous, and widely circulated around the Internet.

There's a great article at NASA's Earth Observatory that describes how they capture these night images of the Earth's surface. You can also see many of the best images taken so far.

Click here to read the article.

Filed under: Earth Observation | 2 Comments »

What happens when a robotic space probe breaks down millions of miles away from the nearest spacecraft engineer? If there is a software bug, engineers can sometimes correct the problem by uploading new commands, but what if the computer hardware fails? If the hardware is controlling something critical like the thrusters or communications system, there isn't a lot mission control can do; the mission may be lost. Sometimes failed satellites can be recovered from orbit, but as there's no interplanetary towing service for missions to Mars. Can anything be done for damaged computer systems far from home? The answer might lie in a project called "Scalable Self-Configurable Architecture for Reusable Space Systems". But don't worry, machines aren't becoming self-aware, they're just learning how to fix themselves…
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Filed under: Space Flight | 13 Comments »

For the first time since docking with the International Space Station (ISS) on April 3rd, the Automated Transfer Vehicle (ATV) "Jules Verne" has been awoken and instructed to carry out an impressive task: push the ISS to a higher orbit. The robotic supply vessel, currently attached to the station's Zvezda module carried out a 12 minute 20 second burn of its main engines. This is the first time an ESA spaceship has carried out such a task and it appears to have performed flawlessly, lifting the 280 tonne station 4.5 km (2.8 miles) to a new altitude of 342 km (213 miles). In true ESA style, they've even released a cool video simulation of the event…
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Filed under: Space Flight, Space Station | 12 Comments »

Humans and sports go hand-in-hand; it was only a matter of time before sports pushed into space. Whether astronauts are practicing their cosmic golf swing, throwing boomerangs (for science of course!), hurling footballs or creating their own unique zero-G activity, we will see some new and inventive space sports in the future…
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Filed under: Space Station | 9 Comments »