The first navigational tool

Image from kaloujm.com

People have been using the sky as their source of navigation for years, and one of the first tools made for the purpose of aiding in navigation (that wasn’t a body part!) was the kamal.  The exact date is unsure, but it’s estimated that this tool came into use around the fifth or sixth century.  While it looks simple, made of just a piece of wood and some string with strategically tied knots along its length, it was highly effective at measuring relatively small angles, allowing ancient navigators to determine their latitude.  It’s used by placing one end of the string between your teeth and extending out the wooden portion attached to the other end of the string an appropriate distance from your face such that the horizon is along the bottom of the wooden board and the star of interest (usually Polaris) to use for navigation is along the top of the board.  The angle is then measured by counting the number of knots which are tied into the string, and this number corresponds to a certain degree of latitude.  There were clear limitations to this tool, as it had a limit with it’s size and that it could only measure a set (pretty small) amount of angles, so it was only very useful in equatorial regions where Polaris remained very near the horizon.  While we have come a long way in navigational tools over the last several centuries, it’s really awesome to see how something so simple can be such a powerful tool when resources and knowledge are limited.

Historical Astronomers in Context

Johannes Kepler is arguably one of the most important astronomers in history.  Kepler was born on December 27, 1571 and died on November 15, 1630.  During his lifetime he was an apprentice to the famous astronomer Tycho Brahe, continuing Brahe’s work after his death. During this time Kepler developed his three laws of planetary motion, which are still prevalent and taught in astronomy classes like ours to this day.  These laws describe the orbit of the planets around the Sun, including the shape of the orbit, the speed throughout different parts of the orbit, and the average time to make a full orbit around the Sun relative to other planets.

During Kepler’s lifetime, there were some other famous historical events going on.  One of which is the Long War between the Habsburgs and the Ottomans in Hungary caused by territorial debates.  This war lasted 15 years from 1591-1606.  Another famous event (that is very near and dear to our hearts) is the founding of Jamestown, Virginia as the first permanent British settlement in North America on May 14, 1607.

Another historical figure who lived during this time is famous sea captain and navigator Sir Francis Drake.  Drake lived from 1540-1596 and is most famous for being only the second explorer (the first British explorer) to circumnavigate the world in one expedition.  This trip took him three years to complete from 1577-1580.

It’s so interesting to note as I looked through what are considered to be “important events” of the time, and this truly was a time of rapid growth and expansion.  All of the key events include discovering new land (*cough* and soon after fighting over who gets to own this new land…*cough*), some new invention, some change in law in the Church.  This was a time when knowledge was growing at a pace faster than we may have ever seen it before.  This is true for astronomy too.  Looking at all of these great astronomers who made so many HUGE advancements in our scientific knowledge and seeing that they all lived within this span of a couple hundred years is just incredible.

The oldest recorded solar eclipse!

After talking about solar eclipses in class yesterday, I got super nerd-ily excited about reading more about them!  A quick wikipedia search (since that is totally acceptable and awesome!) links to tons more wikipedia pages that list the exact date, time, type, location, and path width, among other details.  The oldest recorded one listed on these pages July 10, 1 AD.  So this then got me wondering what the OLDEST recording of a solar eclipse was and how exactly they recorded it.

What I’ve found is that the oldest recordings go way back to a solar eclipse that occurred on November 30, 3340 BC at Loughcrew Cairn L. Megalithic Monument in Ireland.  It’s believed this this particular eclipse obscured nearly 100% of the solar disc. The recordings are made on three separate stones in the location where the eclipse was viewed.  The code that was used to track astronomical discoveries during this time was deciphered by modern astronomers and uses the symbol of overlapping concentric circles to indicate a solar eclipse.  Below are a few really awesome images that the folks at astronomy.ca have created to depict the findings on the stones, as well as what the drawings correspond to in terms of the eclipse (what they believe would have be seen during this eclipse).  It’s crazy to think that these simplistic drawings were possibly the start of the study of solar eclipses that we are still studying today!  I doubt much has changed with the way eclipses work, but I think we have come a long way in how well we are understanding them.

Stone 1:

Stone 2:

Stone 3:

William Herschel believes in ghosts!

picture from: www.redorbit.com

One of my favorite moments in the Neil deGrasse Tyson-hosted show Cosmos: A Spacetime Odyssey takes place in the first moments of one of the first few episodes.  It “flashes back” to the early 1800’s, showing a cartoon involving the famous astronomer William Herschel and his young son, John, walking along the beach on a clear evening.  John looks up at his father and asks, “Father, do you believe in ghosts?”, to which Herschel responds, “Why yes my son”.  Upon seeing his son’s reaction, he clarifies “Oh no, not in the human kind…no, not at all. But look up, my boy, and see a sky full of them”

The young boy has a response typical to the way most would likely respond: confusion and curiosity as to why his father is referring to the stars that they see every night, day after day, as ghosts.  Without a clear understanding of physics and astronomy, and probably even with a good understanding of the subjects, it’s certainly a difficult thought to wrap your head around.  Due to the vast distances that a majority of the stars in our night sky are located away from our planet Earth, along with the limitation that light can travel no faster than well…the speed of light, the light emitted from these stars may take eons to travel to our eyes allowing them to become visible to us.  Some of this light takes SO long to get to us, that there becomes a very real possibility that the stars we are just now beginning to see have already died long ago.  This leaves us with just an image of a body that in our current time, doesn’t exist.  Now, that sounds pretty ghost-like to me!  Although it may not be the most scientific way of describing things, I think that William Herschel was certainly onto something FAR ahead of his time, and something that is still a difficult topic for many to wrap their head around, when he talked to his son about our “sky full of ghosts”.