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Brian Oxley
Works at ThoughtWorks
Attended Rice University
Lives in Houston, TX
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Brian Oxley

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No matter where you go, there you are. Determining where “there” is, however, is another matter.
Brian Koberlein originally shared:
 
From Heaven to Earth

No matter where you go, there you are. Determining where “there” is, however, is another matter.

On Earth we can define our position by three parameters: latitude, longitude, and elevation. Latitude is the angular position that defines how far north or south you are from the equator. Elevation is your height above or below the average level of the oceans. Longitude is your angular position along the equator, relative to some point, which is now Greenwich, England. If you’re navigating at some point along the surface the world, latitude and longitude are the most important things to know.

Latitude is fairly straightforward to determine. As the Earth rotates on its axis, the stars in the night sky appear to revolve around a fixed point in the sky, known as the celestial poles. In the northern hemisphere that point is fairly close (off by only 1°) to the second magnitude star Polaris, so by measuring the angle of Polaris relative to the horizon, you can get a good idea of your latitude. In the southern hemisphere there isn’t a bright star nearby, but you can use the Magellanic clouds to triangulate the south celestial pole.

While careful measurement of the stars can give a very accurate measure of latitude, it isn’t something easily done at sea. So instead, latitude was determined using a sextant to measure the angular position of the Sun at local noon, when it is highest in the sky. As long as it is a clear day, measuring the angle of the Sun is quite easy. The catch is that unlike the celestial poles, the angular height of the Sun at noon varies with the seasons. So you also need to know the date and have a table (or do the trigonometric calculation) that tells you the latitude at which the Sun would pass directly overhead that day. By taking this into account, you can then determine your latitude.

Longitude, however, is another matter. For one, unlike latitude it is reckoned relative to an arbitray point. We use Greenwich, England, but we could just as easily use Poughkeepsie, New York. For another, there is no simple way to use the Sun or stars to determine longitude. Given the importance of longitude, lots of methods have been proposed over the years, but until recently one of the more accurate methods was to use the moons of Jupiter.

When Galileo discovered four moons of Jupiter in the early 1600s, he noticed that their motions followed Kepler’s laws. This clockwork precision meant that the Jovian system could be used as a “heavenly clock” to determine the time. One way this could be done was by observing when the moons entered-or-exited the shadow of Jupiter as they passed behind the giant planet. Even with a small telescope, one could observe a moon fade to darkness over the course of a few minutes as it entered the shadow, or gradually brighten as it left the shadow on the other side.

With a table listing the predicted times of these eclipses as seen from a particular observatory, one could know the exact local time at that observatory. By comparing that with the time that you measured your local noon to be, you could then determine the time difference between your location and the observatory. Knowing that the Earth rotates 360 degrees in a day, you could then determine your longitude relative to the observatory.

Galileo went so far as to calculate time tables for these eclipses, but they weren’t accurate enough to be very useful. Then in 1668 Giovanni Domenico Cassini published the first truly accurate table of Galilean eclipses. Cassini’s tables were so accurate that they redefined the shape of Europe. The distances between cities as given since the Roman Empire were found to be hundreds of kilometers off. You can see this in the maps of Europe before and after Cassini’s tables.

Despite its accuracy, the Galilean method of longitude had some serious drawbacks. There are times when Jupiter is too close to the Sun for the moons to be observed, and the method was completely useless while at sea. By the late 1700s John Harrison’s marine chronometer became the preferred method for calculating longitude at sea, but well into the 1800s Galileo’s method was preferred for land explorers. Chronometers were both expensive and fragile, so a small telescope was the preferred tool.

Modern methods have now replaced Galileo’s moons as a method of calculating longitude, but the moons of Jupiter were a huge step forward that quite literally changed the face of the world.
Determining your position on Earth used to be an astronomical problem, and the discovery of Jupiter's moons made that task much easier.
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35 moments in the 15-year journey to get billions of miles away from Earth.
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I thought dogs came from bitches.
An unprecedented alliance hopes to figure out where and when our canine pals arose
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Holy Buck Rogers, Batman!
General Atomics displays a small, self-contained, weapons-grade laser cannon that can be attached to the roof of your car
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Lengthy, detailed. Great graphs.
 
Thanks +Peter Friedman 
tl;dr: Storage of electricity in large quantities is reaching an inflection point, poised to give a big boost to renewables, to disrupt business models across the electrical industry, and to tap into a market that will eventually top many of tens of billions of dollars per year, and trillions of ...
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Dark matter and the Large Hadron Collider (link was missing from yesterday's post)
Dark Matter. Its existence is still not 100% certain, but if it exists, it is exceedingly dark, both in the usual sense --- it doesn't emit light or reflect light or scatter light --- and in a more...
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Brian Oxley

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For more than four years NASA's MESSENGER spacecraft has been orbiting our solar system's innermost planet Mercury, mapping its surface and investigating its unique geology and planetary history in...
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Brian Oxley

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Clowns the left, jokers to the right.
Guest essay by S. Fred Singer (originally published on American Thinker reprinted here with permission of the author. I endorse this opinion, though not the personal labels. We can all do with less...
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For the first time dark matter may have been observed interacting with other dark matter in a way other than through the force of gravity. Observations of colliding galaxies have picked up the first intriguing hints about the nature of this mysterious component of the Universe.
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Have him in circles
344 people
Mike Deck's profile photo
Syful Islam's profile photo
Nicolae Duca's profile photo
Jean-Marie Dautelle's profile photo
Rodrigo Silveira's profile photo
Brian Yoffe's profile photo
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Alison Cook's profile photo
Education
  • Rice University
    Physics, Music, 1987 - 1991
  • Trinity University
    Physics, Music, 1985 - 1987
Basic Information
Gender
Male
Other names
binkley
Story
Introduction
It's just me.
Bragging rights
Best wife ever. Two wonderful sons. Full Moria armor set.
Work
Occupation
Principal Consultant
Employment
  • ThoughtWorks
    Principal Consultant, present
  • Macquarie Offshore Services
    Sr. Manager, 2013 - 2015
    IT Manager
  • Macquarie Group Limited
    Sr. Manager, 2010 - 2013
    Java Architect
  • ThoughtWorks
    Open Sourcerer, 2003 - 2004
    Developer
  • SimDesk
    Sr. Engineer
    Developer
  • Novasoft
    Software Engineer
    Developer
  • Merrill-Lynch
    Contractor
  • JPMorgan Chase & Co.
    Sr. Associate, 2006 - 2010
    Sr. Developer
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
Houston, TX
Previously
Makati, Philippines - Three Rivers, TX - Boston, MA - San Antonio, TX
Links
Brian Oxley's +1's are the things they like, agree with, or want to recommend.
Houston's Rice University Business Plan Competition grand prize winner K...
www.bizjournals.com

The Rice Business Plan Competition gave out roughly $1.5 million to companies from around the world. The largest business plan competition i

Best Colonization target in outer solar system is Titan
nextbigfuture.com

Titan is suggested as a target for colonization, because it is the only moon in the Solar System to have a dense atmosphere and is rich in c

gotofail and a defence of purists | Lockstep
lockstep.com.au

gotofail and a defence of purists. Stephen Wilson, Wed 26 Feb 2014 - 1 Comment. 'The widely publicised and very serious "gotofail" bug in iO

Steve Yegge's Next Big Language Revisited
lebo.io

Steve Yegge's Next Big Language Revisited. March 2 2015. Tweet submit to reddit submit to Hacker News. Good old Steve Yegge. For several yea

Thai Pop-Up Dinner in Houston by New York Chef Hong Thaimee
blogs.houstonpress.com

New York Chef Hong Thaimee has come to Houston to present two nights of a pop-up dinner featuring her take on Thai food.

Four Tips for Managing Performance in Agile Teams
www.jrothman.com

I've been talking with clients recently about their man…

How Singapore Became an Entrepreneurial Hub
hbr.org

Things are heating up in the former “Singa-bore.”

What is the weak force?
briankoberlein.com

The weak force is what causes radioactive decay. It's also what has made life on Earth possible.

Internet Freedom Works
www.politico.com

For the past two decades, Internet freedom has been a remarkable success story. It has given the American people unprecedented access to inf

Could classical theory be just as weird as quantum theory?
phys.org

Quantum mechanics is often described as 'weird' and 'strange' because it abandons many of the intuitive traits of classical physics. For exa

The most backwards moon in the solar system
briankoberlein.com

Triton is Neptune's largest moon, and the largest moon it the solar system to orbit backwards.

How Can Space Travel Faster Than The Speed Of Light?
www.universetoday.com

Cosmologists are intellectual time travelers. Looking back over billions of years, these scientists are able to trace the evolution of our U

Scientists find strongest natural material known to humans
www.sciencedaily.com

Limpet teeth might be the strongest natural material known to humans, a new study has found. Limpets -- small aquatic snail-like creatures w

Ada the Amplifier
rjlipton.wordpress.com

Plus updated links to our Knuth and TED talks Ada Lovelace was nuts. Some have used this to minimize her contributions to the stalled develo

Interesting Plausibility that Elon Musk Could Become a Trillionaire with...
nextbigfuture.com

Some have called the Elon Musk comment that Tesla Motors could reach $700 billion in market valuation by 2025 with 50% per year annual reven

Scientists get first glimpse of a chemical bond being born
phys.org

Scientists have used an X-ray laser at the Department of Energy's SLAC National Accelerator Laboratory to get the first glimpse of the trans

The Spectacular Too Big Failure of Dodd-Frank
www.thefiscaltimes.com

Not much unites the activist Left and activist Right, and not much ever has.

One of our favorite places in the Philippines. The staff was excellent, lacked for nothing. The nearby national parks are grand. Well recommended. Do note this is a "green" resort. Hot water is solar-heated, which may provide a surprise for your morning shower. We look forward to staying here again.
Public - 4 months ago
reviewed 4 months ago
Some of the best customer service I've had in a long time. They had similar products to what I wanted but not exactly. So they looked up the number of a competitor, wrote it down, and offered to call.
Quality: ExcellentAppeal: ExcellentService: Excellent
Public - 2 years ago
reviewed 2 years ago
The best, of course.
Appeal: ExcellentFacilities: ExcellentService: Excellent
Public - 2 years ago
reviewed 2 years ago
23 reviews
Map
Map
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Great environment, excellent staff, competitive pricing.
Public - a year ago
reviewed a year ago
First class traditional men's business clothing. You pay for quality.
Quality: ExcellentAppeal: ExcellentService: Excellent
Public - 2 years ago
reviewed 2 years ago
It really is Tex-Mex like your grandfather ate.
Food: ExcellentDecor: Very GoodService: Excellent
Public - 2 years ago
reviewed 2 years ago