Congrats muskie dave, Phyzicist, and Sharpeye468 on the joint First to Find!
CACHE IS NOT AT POSTED COORDINATES
jiggs11 gets bonus points for catching an error that everyone, including me, missed!
I added a dangerous animal attribute, because I saw a skunk not 100 metres away when I placed this. So that’s kinda tongue in cheek, but there are black bears around, and some locals swear up and down we’ve got cougars around too (MNR flatly denies this), so make of it as you will.
In 1933 the city of Chicago hosted a World’s Fair. At the time this newfangled technology called a photocell was all the rage. Powering a device with nothing but the sun? Ludicrous! Now, 40 years previous Chicago had hosted a different huge festival. And in this era, Arcturus was thought to be 40 light years away. What better way to turn on the lights on the first day than by using the light from an easy to see star (-0.05 apparent magnitude) that was forty years distant, light that emanated from the star at the first exposition and arrived in time for the next? Four observatories were chosen to host photocells (in case of clouds), and they each collected light from Arcturus through a telescope and sent it along the telegraph line to the fairgrounds in Chicago, and at 9:15pm on May 27, 1933, the switch was thrown, and a bright searchlight on top the Hall of Science illuminated the sky. It was a huge hit.
It turns out Artcurus is actually 36.7 light years away, so the old-timey Chicagoans were a bit off on their timing. It wasn’t until the 1990s that science began to get really accurate measurements of just how far away these things are. And oftentimes, those measurements aren’t precise either. So we can let the Windy City folks off the hook.
Arcturus is actually the brightest star in the northern half of the sky. What does that mean? The sky is divided into two halves, north and south, with the divider being the ecliptic. What’s the ecliptic? It’s the plane of our solar system. It’s the path in the sky the sun, moon, and planets follow. The brightest star north (above) that line is Arcturus. Second brightest is Vega. Arcturus is distinctly orange in appearance, and is easy to find in the night sky. Even if you know next to nothing about the stars. Everybody knows the Big Dipper, right? You can use it to “star hop” to Arcturus. Just “arc to Arcturus”. Look at the stars at the end of the handle, and if you follow the curve at of the end of the handle, you will come to a rather bright orange point of light. That is Arcturus! I’ll put in a photo from Earthsky.org that shows how to do that (great website, folks).
If you did my first astromystery cache Vega, you’ll remember that the colour of a star is a clue to how hot it is. Arcturus is orange. That means it’s cool (relatively). From hottest to coolest, the colours go blue -> white -> yellow -> orange -> red. That means its cooler than your garden-variety star. Cooler being a relative term, it’s surface temperature is something like 4000°C, or for the Fahrenheit inclined, 7250°F. That’s about 1500°C colder than our own star. Vega, the second brightest star in the northern sky, burns at around 9400°C.
Does that mean Arcturus is puny? No, actually. Arcturus is actually classed as a red giant – a K0III type star. The K represents its “temperature group”. The scale has a strange letter order: O B, A, F, G, K, and then M. Our sun is a G type star, and Vega is an A type star. Each letter is subdivided (0 through 9) based further on temperature. A K0 star is hotter than a K1 star, for example. The III is its luminosity class. Stars aren’t just grouped by temperature, each category is subdivided based on how much energy they output. And how much energy they output is a function of both how hot and how big they are. The larger the star, the (generally) greater the output. This scale uses (mostly) Roman numerals: 0, I, II, III, IV, V, and also D for dwarfs. V is main sequence (think our sun, or Vega), and III is giant. So as Arcturus is a K0III type star, that means its among the hottest stars in the second coolest grouping of them, and is a giant.
Just how giant? Well, Earth is something like 12,000 kilometres in diameter. Our sun is about 1,391,400 kilometres in diameter. Arcturus is something in the neighbourhood of 36,000,000 kilometres across. It’s this large because it’s old, over 7 billion years old. Stars are powered by fusion taking place in their cores. They’re mostly hydrogen, and their gravities are so intense that the hydrogen in the core fuses together to form heavier elements. When a star uses up all its available hydrogen, it expands. Arcturus once was a size similar to our sun. In turn, when our star uses up its hydrogen, it will expand just like Arcturus and become a giant too. Despite it being so much larger, Arcturus has roughly the same mass as our sun.
Here’s where things get kind of weird with Arcturus. Most stars you can see in the night sky revolve around the centre of our galaxy. There is a supermassive black hole with a gravity so great that a few hundred billion stars circle around it. The same way the planets revolve around the sun, or the moon revolves around Earth. Not Arcturus though. Relative to our solar system, Arcturus is hurtling through the galaxy at 122 km/s, and is cutting perpendicularly through it. As a result, it is actually moving closer to us, and in about 4000 years it will reach its closest point (which will still be *really* far away). And then eventually it will disappear from the night sky, as it travels further away. Why does it travel in such a manner? It’s not known for sure. It may be that Arcturus is a visitor to our galaxy, an extragalactic entity that is just passing by.
Thanks to its prominence in the night sky, there is a lot of lore attached to Arcturus. The name itself is one of the few remaining Greek star names still in use, it derives from the ancient Greek for bear (arktos) and watcher/guardian (ouros). So it’s Greek for “Guardian of the Bear”. It’s the most prominent star in the constellation Boötes the Herdsman (and as such was given the designation Alpha Boötis), and it is adjacent to the two bears in the sky, Ursa Minor and Ursa Major. Depending on which translation is used, the star is one of the few mentioned in the Bible (Job 9:9 in the King James Version).
In Inuit folklore there is a tale of a young boy (lliarjugaarjuk), who when visiting his grandmother (Ningiuq), was taunted by an old man (Uttuqalualuk). The old man, in his own youth, murdered his younger brother, and this was unknown to almost all. The grandmother knew, however, and told the young boy to taunt back at the old man that he knew the old man was a killer. One day the young boy mustered up the courage to yell that, and so the old man grabbed a knife and began to chase the young boy around an igloo. The grandmother saw the commotion and rushed to help. In the night sky, Kingullialuk (Vega) represents Ningiuq and is coming towards Sivulliik “the two in front” (Uttuqalualuk the old man, represented by Arcturus; and Iliarjugaarjuk the young boy, which is the star Muphrid).
In Polynesia the star is known as Hōkūleʻa, which means Star of Joy. It is directly overhead of Hawai’i so Polynesian sailors would use the star as a guide to find the island chain. Departing from Tahiti one only needs to head towards Hōkūleʻa to find the Big Island. In Vedic astrology in India the star is known as Swati, a Sanskrit word meaning “Very beneficent”. One of the Hindu lunar mansions is of the same name. What is a lunar mansion? Just a segment of the ecliptic. The zodiac is a set of lunar mansions. In Babylon around 3,400 years ago, Arcturus was listed in the MUL.APIN sky catalogue as SHU.PA, though what that translates to is unclear. It was one of the stars of Enlil, the Sumerian god of storms.
Fill in the missing numbers to get the coordinates:
N 44 ab.cde
a = Arcturus is _500° colder than our own sun.
b = Arcturus is _ billion years old.
c = Arcturus’s apparent magnitude is -0.0_.
d = Arcturus is mentioned in the Bible in the verse Job _:9.
e = Arcturus is a K_III type star.
W 078 fg.hij
f = Arcturus’s effective temperature is 4_00 degrees Celsius.
g = The ancient Mesopotamian tablet that mentions Arcturus as SHU.PA is _,400 years old.
h = Arcturus’s luminosity class is _.
i = Arcturus will be at its closest point to us in _,000 years.
j = The light from Arcturus was used to kick off the 1933 Worlds Fair on May _7.
And if you're familiar with celestial coordinates, the star can be found in the night sky at RA: 14h 15 m 39.7s, dec: +19° 10′ 56″
You can check your answers for this puzzle on GeoChecker.com.