Mayur's Posterous

How many habitable planets are there in the galaxy? | Bad Astronomy | Discover Magazine

gliese581c
By now you may have heard the report that as many as 1/4 of all the sun-like stars in the Milky Way may have Earth-like worlds. Briefly, astronomers studied 166 stars within 80 light years of Earth, and did a survey of the planets they found orbiting them. What they found is that about 1.5% of the stars have Jupiter-mass planets, 6% have Neptune-mass ones, and about 12% have planets from 3 – 10 times the Earth’s mass.

This sample isn’t complete, and they cannot detect planets smaller than 3 times the Earth’s mass. But using some statistics, they can estimate from the trend that as many as 25% of sun-like stars have earth-mass planets orbiting them!

 

 

Like mass?

Now, there’s a very important caveat here: these are planets that have the same mass as Earth, but that doesn’t mean they are very earth-like. The planets the team could find were very close to their parent stars, so they’d be very hot, and uninhabitable. But the good news is that if that trend in mass they saw is correct, the Milky Way is littered with planets the mass of the Earth! If some of them are in the habitable zone of their star… well.

spitzermilkyway_sunscalebar
So a funny thing: I was thinking about this very problem a couple of days ago, but from a different angle. How many habitable planets are there in the Milky Way? Not just earth-mass, but also orbiting their star in the so-called Goldilocks Zone, where temperatures are right for liquid water?

There’s a way to estimate it. And it involves the planet recently announced, Gliese 581g. This planet is about 3 times the Earth’s mass, and it orbits its star in the right place. We don’t know what it’s made of, if it has an atmosphere, or really very much about it at all! But given its mass and temperature, it’s potentially habitable.

The distance to the Gliese 581 system is what gets me excited: it’s 20 light years away. That’s close, compared to the vast size of our galaxy. So let’s assume Gliese 581g is the closest potentially habitable planet to us. Given that assumption, we can estimate the number of potentially habitable planets in the entire Milky Way! And the math’s not even that hard.
 

 

The not-so-hard math

Extrapolating from our one example, let’s say that habitable planets are roughly 20 light years apart in the galaxy (as we’ll see, that number can be a lot bigger or smaller, and the end result is still cool). That means there’s one star per cube 20 light years on a side:

sun_twocubes

In the drawing, each box is centered on a star, and the two stars are 20 light years apart. That means the cubes are 20 light years on a side, right? If we assume stars with livable planets are distributed throughout the galaxy like this, then there is one star per 20 x 20 x 20 = 8000 cubic light years. That’s the density of habitable planets in the galaxy.

So how many cubic light years are there in the galaxy?

A lot. Let’s say the Milky Way is a stubby cylinder 100,000 light years across, and 2500 light years thick. The equation of volume of a cylinder is

volume = π x radius of disk2 x height of disk

so

volume = π x 50,0002 x 2500 = 2 x 1013 cubic light years

Holy wow! That’s 20 trillion cubic light years!

Now we just divide the volume of the galaxy by the density of stars with planets to get

2 x 1013 / 8000 = 2,500,000,000 planets

Oh my. Yeah, let that sink in for a second. That’s 2.5 billion planets that are potentially habitable!

 

 

What does this mean?

Well, that’s a whole lot of planets! That’s what it means.

What’s cool, too, is that this number isn’t all that far off from what you can estimate using the report from yesterday. Something like 25% of the stars in the galaxy are like the Sun (that’s a rough estimate, but close enough). That’s 50 billion stars. If 25% of those have earth-mass planets, that’s about 13 billion total, about five times the number I got. I’d call that pretty close! We made a lot of guesses here, so even a factor of ten isn’t so bad. And we’re not really comparing apples to apples, either, since they were looking for earth-mass planets, and I was looking for earth-like planets.

So think about it: 2.5 billion habitable planets is roughly enough for every man, woman, and child on Earth to each have a planet. You can see why I’m not too concerned with the exact math. Even if my numbers are way off, there could be as few as hundreds of millions of planets, or as many as maybe hundreds of billions in our galaxy alone that we could live on!

Again, the point being that mathematically speaking, there may be a lot of habitable planets out there. And who knows; some may be marginally habitable and we can terraform them. And then there are moons of worlds, too… I don’t think I’m speaking too far out of school if I were to speculate that for every perfect Terra Nova out there, there might be three or four more planets we could live on with some work.

Of course, I’m ignoring how we’d get there! But that’s an engineering problem, and given enough time — oh, say, a century or two — I imagine we can overcome a lot of those issues.

If, and when, we do, there will be a lot of real estate out there to poke around in.

Per ardua, ad astra!

 

 

Posted

Awesome Vintage Tech Ads | UNEASYsilence

      

 


You can laugh now, but some years ago you were getting a very nice deal by buying a $3398 10MB hard drive.

 

 

 


A sexy modem? Come on!

 


 

 

 


 


Two are always better than one. At least according to this 1978 ad from Technico Inc. TMS9900.

 

 

 


Remember Elvira, Mistress of the Dark? Besides appearing on TV in features like Elvira’s Movie Macabre Halloween Special, Elvira also invited Computerworld readers to “cut through paper-based CASE [computer-aided software engineering] methods with LBMS” software.

 


This ad won’t make any sense if you’re not a follower of the TV series Lost. However, if you are, you’ll find it amusing…

 

 


It’s small and light at ‘only’ 11+ lbs.

 

 

 


“With WordStar, you have a true screen image of what your printout will look like before you print it! With WordStar, you’ll erase, insert, delete and move entire blocks of copy.” Gee, it’s like magic!

 

 


 

 


Would you say this ad was a little sexist?

 

 


 

 


Every Kid Should Have an Apple after School.

 

 


In the future, everyone will use floppy disks.

 

 

 

Posted

Colleyville Heritage girls give up makeup for beauty's sake | Schools | News from Fort W...

By Shirley Jinkins

COLLEYVILLE -- On Tuesdays, about 180 girls at Colleyville Heritage High School leave their lipstick and eye shadow at home, attending classes with clean faces and fresh attitudes.

They also wear matching T-shirts that read, "Redefining Beautiful, One Girl at a Time."

Media_httpmediastarte_kbyzc

 

Redefining Beautiful is a new student club meant to empower girls to resist stereotypes based on appearance.Samantha Gibbs, Lauren Gilby, Nina Smith, Caroline Tessler, Emily Gates and Laura Kelly came up with the idea during the summer.

"We're not against wearing makeup," said Nina, 16, a junior. "We're really against girls feeling like it's a shell to hide in."

The girls got the general idea from a website, www.OperationBeautiful.com, and decided to adapt the positive messages to a program that would fit at Colleyville Heritage. The website encourages teen girls to share their stories and to post anonymous encouraging messages in public places for other women and girls to find.

The friends recruited faculty sponsor Suzanne McGahey, made sure that their club met the criteria for a school-sanctioned organization and began signing up members shortly after classes started in August.

Six more of their friends joined them as charter members.

"We had more than 170 girls signed up within three or four weeks," McGahey said. "I don't know what they hit on, but it obviously made an impression."

Bill Gibbs, Samantha's father, said he was shocked at how quickly the club caught on.

"We ordered 25 shirts at first, and now there are 183 girls signed up," Gibbs said.

The girls say they expected maybe 40 girls to join.

"It was awkward the first couple of Tuesdays when there were just 12 of us," said Caroline, a 17-year-old senior. "People would ask, 'What are you doing?'"

Many girls have joined the cause, they say, but not all of them can kick the makeup habit.

"There have been a couple of girls we've asked to join that have said, 'I don't think I could do that,'" said Emily, 17, a senior. "It's encouraged me to not worry about makeup on other days besides Tuesdays."

The idea is spreading. Students at Grapevine High School are also interested in forming their own Redefining Beautiful club, and Southlake girls have expressed interest.

Even the guys at Colleyville Heritage are on board, with 20 boys forming a support group.

"That's all we're trying to prove -- that girls can be just as confident with or without makeup," said Lauren, also 17 and a senior.

Students plan to embrace women- and child-oriented service projects, including a Thanksgiving food drive and clothing drive for Christmas.

"It's wanting to share our story that no matter what has happened to you, you're beautiful and you should love yourself," Caroline said.

Redefining Beautiful members include classroom leaders, athletes and quieter types.

"We try to get the young girls to know that beauty is more about who you are than what you wear to school," McGahey said.

School counselor Robin Davis said the negative effects of marketing and entertainment on girls and women are seen all too often.

"It's the way our culture is; image and what you look like, what you wear," Davis said. "It contributes to the incidence of teens with eating disorders and other ways of changing their appearance, whether it be tanning or makeup."

No one associated with Redefining Beautiful has encountered negative comments from students, staff or parents, McGahey said.

Davis, an early fan of the group, wears her own Redefining Beautiful shirt Tuesdays and goes easy on makeup.

Gibbs is proud of his daughter and her friends.

"I think it's good for their self-esteem because they're focused on what's most important instead of the superficial," he said. "They were able to start something and make it work, and do something good with it. They're making a positive difference."

Shirley Jinkins, 817-390-7657

Looking for comments?

Kudos to these young women. I don't usually judge anyone but a kilo of makeup on a girl's face is an instant turnoff for guys like me.

Posted

Boeing gets $89M to build unmanned aircraft that can stay aloft for 5 years

darpa/boeing solareagleOne of the more unique unmanned aircraft took a giant step toward reality this week when the Defense Advanced Research Projects Agency (DARPA) inked an agreement with Boeing to build the SolarEagle, a plane capable of remaining at heights over 60,000ft for over five years.

Boeing says the first SolarEagle under the $89 million contract could fly as early as 2014.

12 mad science projects that could shake the world

The SolarEagle is built under DARPA's Vulture program.  The idea is to build a single aircraft that could support traditional intelligence, surveillance, and reconnaissance functions over country-sized areas - while at the same time providing an unblinking eye over a critical target, monitoring that target night and day, day in and day out, month after month - providing unprecedented high-value intelligence. Vulture aircraft will also be able to provide communications capabilities available today only from geostationary satellites - offering opportunities for new, more flexible, expandable and relocatable communication architectures at a fraction of the cost of dedicated satellite capabilities. The challenges with Vulture include developing solar cell, energy storage, and reliability technologies that will allow the aircraft to operate continuously, unrefueled for over 44,000 hours, DARPA stated.

Under the Vulture II agreement, Boeing will develop a full-scale flight demonstrator, including maturation of the critical power system and structures technologies. Key suppliers for the program include Versa Power Systems and QinetiQ. 

During testing, the SolarEagle demonstrator will remain in the upper atmosphere for 30 days, harvesting solar energy during the day that will be stored in fuel cells and used to provide power through the night. The aircraft will have highly efficient electric motors and propellers and a high-aspect-ratio, 400-foot wing for increased solar power and aerodynamic performance, Boeing stated.

Boeing has been on a roll this week.  Earlier it had announced a marriage with outer space tourism proprietors Space Adventures to offer low Earth orbit (LEO) flight services onboard Boeing's future commercial crew spacecraft.  Under the agreement, Space Adventures will market passenger seats on commercial flights aboard the Boeing Crew Space Transportation-100 (CST-100) spacecraft.

Boeing's (CST)-100, which is under development, can hold seven and is bigger than NASA's Apollo orbiter but smaller than NASA's Orion.  Boeing says the ship will be able to launch on a variety of different rockets, including Atlas, Delta and Falcon. It will use simple systems architecture and existing, proven components, Boeing stated.

Follow Michael Cooney on Twitter: nwwlayer8  

 

 

 

Posted

'Facebook users have low self-esteem' - The Times of India

Posted

Naked Black Hole Builds Future Galactic Dream Home | Wired Science

phot-46a-09-fullres-2

Astronomers have spied a distant black hole in the act of creating the galaxy that will eventually become its home.

By sending a jet of gas and highly energetic particles into a neighboring galaxy, the black hole has touched off star formation at a rate 100 times the galactic average.

“Our study suggests that supermassive black holes can trigger the formation of stars, thus ‘building’ their own host galaxies,” David Elbaz, lead author of a paper on the work in the journal Astronomy and Astrophysics, said in a press release. “This link could also explain why galaxies hosting larger black holes have more stars.”

phot-46b-09-fullresThe quasar HE0450-2958, located about 5 billion light-years from Earth, is powered by a supermassive black hole. Unlike all other known quasars, this one did not appear to be surrounded by a galaxy, which had puzzled astronomers. They thought perhaps the quasar’s surrounding galaxy was obscured by dust.

So, in the latest observations they looked in the mid-infrared part of the spectrum, in which dust shines brightly, using the European Southern Observatory’s Very Large Telescope. But they didn’t see dust, confirming the idea that the quasar really is “naked.”

Instead of a surrounding galaxy, Elbaz’s team found the black hole was blasting its neighbor with energy and matter. That injection has caused the observed flurry of star births: 350 new suns are bursting into existence each year in the region.

Eventually, the black hole will merge with its neighbor. The two objects are located 22,000 light-years apart and are moving towards each other at less than 125 miles per second. In tens of millions of years, HE0450-2958 will finally get a home.

“This would provide a natural explanation for the missing host galaxy,” Elbaz and his co-authors wrote.

Images: 1) Artist’s rendering of HE450-2958 and its galactic neighbor.
2) Composite image of HE450-2958 composed of imagery from Hubble, Very Large Telescope, and the Advanced Camera for Surveys.

See Also:

WiSci 2.0: Alexis Madrigal’s Twitter, Google Reader feed, and green tech history research site; Wired Science on Twitter and Facebook.

Posted

Laws of physics vary throughout the universe, new study suggests

Posted

gulfnews : Three arrested for offering VoIP services

Police said the three men from Bur Dubai, Satwa and Hor Al Anz, were offering illegal international calls using IP technology. The suspects allegedly charged 50 fils per minute for the calls and used their apartments to sell the service.

Lieutenant Colonel Salim Al Rumaithi, Deputy Director of the Criminal Investigation General Department of Dubai Police, said police received a tip-off last month about three suspects allegedly offering international phone calls at a cheap price.

"These types of crimes are very serious, and according to the tip-off the department organised a team to investigate the case," said Major Salah Bu Aseeba, Director of the Department of Economic Crimes at Dubai Police.

On the same day the tip-off was received, police said they organised three teams to raid the three locations and arrest the suspects. A.B. was picked up from the Hamdan area, M.A. from Hor Al Anz and M.A. from Satwa, police said. A search of their apartments yielded multiple mobile phones and wireless communication equipment and computers.

All three confessed to illegally operating voice-over internet protocol channels and were handed to the authorities for further procedures, police said.

Brigadier Khalil Ebrahim Al Mansouri, Director General of the General Department for Criminal Investigation, said that these types of crimes caused a lot of damage to telecom providers, intellectual copyright, and the country's economy.

 

Posted

Interactive Graphic on the food that soilders eat around the world.

Posted

NASA plans to send a probe to the Sun.

SOLAR SCIENCE

 

Solar Probe Plus To Plunge Directly Into Sun's Atmosphere

Solar Probe+ will likely discover new mysteries, too, in a realm that no other spacecraft has dared enter. At closest approach, Solar Probe+ will be 7 million km or 9 solar radii from the sun. There, the spacecraft's carbon-composite heat shield must withstand temperatures as high as 2000 degrees C and survive blasts of radiation that would quickly disable other missions. From these near distances inside the sun's atmosphere, the solar disk will loom 23 times wider than it does in the skies of Earth.
by Dr. Tony Phillips
Science@NASA
Huntsville AL (SPX) Sep 03, 2010
NASA's daring plan to visit the sun took a giant leap forward with the selection of five key science investigations for the Solar Probe+ spacecraft.

Slated to launch no later than 2018, the smart car-sized spacecraft will plunge directly into the atmosphere of the sun, aiming to solve some of the biggest mysteries of solar physics. The announcement means that researchers can begin building sensors for unprecedented in situ measurements of the solar system's innermost frontier.

"Solar Probe+ is going where no spacecraft has gone before," says Lika Guhathakurta, Solar Probe+ program scientist at NASA HQ. "For the first time, we'll be able to 'touch, taste and smell' the sun."

Last year, NASA invited top researchers around the world to submit proposals detailing possible science investigations for the pioneering spacecraft. Thirteen proposals were received and five have been selected:

+ SWEAP, the Solar Wind Electrons Alphas and Protons Investigation: The most abundant particles in the solar wind are electrons, protons and helium ions. SWEAP will count these particles and measure their properties, even "sweeping up" some of them in a special Solar Probe Cup for direct analysis. The principal investigator is Justin C. Kasper of the Smithsonian Astrophysical Observatory in Cambridge, Mass.

+ WISPR, the Wide-field Imager for Solar Probe Plus: WISPR is a telescope that will make 3D images of the sun's atmosphere similar to medical CAT scans. WISPR can actually see the solar wind, allowing it to image clouds and shock waves as they approach and pass the spacecraft. This telescope is an important complement to the spacecraft's in situ instruments, which sample the plasmas that WISPR images. The principal investigator is Russell Howard of the Naval Research Laboratory in Washington, DC.

+ FIELDS, The Fields Investigation for Solar Probe Plus: This instrument will make direct measurements of electric and magnetic fields, radio emissions, and shock waves which course through the sun's atmospheric plasma. FIELDS also turns Solar Probe Plus into a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna. The principal investigator is Stuart Bale of the University of California in Berkeley.

+ ISIS, Integrated Science Investigation of the Sun: The ISIS EPI-Hi and EPI-Lo instruments will monitor electrons, protons and ions which are accelerated to high energies by shock waves in the sun's atmosphere. These are the very same particles that pose a threat to astronauts in space, disable satellites, and ionize Earth's upper atmosphere.

+ Solar Probe+ Observatory Scientist: This was a proposal not for an instrument, but for a person. The principal investigator, Marco Velli, becomes the mission's Observatory Scientist. In the years ahead, he will become deeply familiar with the spacecraft and its construction, helping to ensure that adjacent in situ instruments do not interfere with one another as they sample the solar environment. He will also guide the mission's "big picture" science investigations after Solar Probe+ enters the sun's atmosphere.

"The sensors we've selected to ride aboard Solar Probe+ are designed to solve some of the biggest mysteries of solar physics," says Dick Fisher, head of NASA's Heliophysics Division in Washington DC.

Why is the sun's atmosphere is so much hotter than its surface? And what propels the solar wind?

"We've been struggling with these questions for decades," says Fisher. "Solar Probe+ should finally provide some answers."

Solar Probe+ will likely discover new mysteries, too, in a realm that no other spacecraft has dared enter. At closest approach, Solar Probe+ will be 7 million km or 9 solar radii from the sun. There, the spacecraft's carbon-composite heat shield must withstand temperatures as high as 2000 degrees C and survive blasts of radiation that would quickly disable other missions. From these near distances inside the sun's atmosphere, the solar disk will loom 23 times wider than it does in the skies of Earth.

"What will we find there?" wonders Guhathakurta. "This is truly unexplored territory." By design, Solar Probe's winning instruments are sufficiently versatile to investigate many different kinds of phenomena. Whatever comes along--be it electric or magnetic, high- or low-energy, wavy or turbulent--they should be able to measure it.

"The possibilities for discovery," she says, "are off the charts."

Here's NASA's website for the project http://solarprobe.gsfc.nasa.gov/

Posted