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Ep. 25 Southern Stars - HD and the Void

I live in the Northern Hemisphere of Earth, which means I see some constellations and stars that people in the Southern Hemisphere don't see. The opposite is true as well, and it's more interesting for me to talk about the constellations I don't g...

I’m a Northern Hemisphere dweller, so I thought it would be fun to cover Southern Hemisphere stars and constellations in this episode! I also coulsnt’ resist talking about Aurora Australis and Steve, the hot new atmospheric phenomenon all the young people are talking about.

Below the cut, I have the glossary, transcript, sources, and music credits. I take topic suggestions from Tumblr messages, or you can tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Please subscribe on iTunes, rate my podcast and maybe review it, and tell friends if you think they’d like to hear it!

(My thoughts on the next episode are Chuck Yeager, Stephen Hawking and his theories, the opposition of Mars, or famous comets. The next episode will go up May 14th or 21st!)

Glossary

Bayer designation - a way to classify stars based on their relative brightness within a constellation. A specific star is identified by a Greek letter, followed by the genitive form of the constellation's Latin name.

circumpolar - appearing to orbit one of the Earth’s poles. For stars and constellations, this means they are above the horizon at all times in certain latitudes.

irregular galaxy - an asymmetrical galaxy shape, where the galaxy lacks a central supermassive black hole.

Script/Transcript

Sources

Orion from the Southern Hemisphere via EarthSky (Mar 2017)

How to Spot Sky Landmarks: Big Dipper and Southern Cross via Space.com (Apr 2012)

Locate Cassiopeia the Queen via EarthSky (February 2018)

Small Magellanic Cloud orbits Milky Way via EarthSky (Oct 2017)

Nubecula via LatDict

Early star catalogues of the southern sky via Astronomy and Astrophysics (2011)

Catalog of Southern Stars via the University of Oklahoma

Edmond Halley via Royal Museums Greenwich

Finding south using the Southern Cross via Museum of Applied Arts and Sciences (Jan 2013)

List of 88 official constellations via the Astronomical Society of Southern Africa

Alpha Centauri system, closest to sun via EarthSky (May 2017)

Hadar is a southern pointer star via EarthSky (April 2017)

Aurora Australis forecast service

Video of aurora australis via Global News Canada (April 2018)

Aurora Steve via Global News Canada (March 2018)

Bagnall, Philip M. “Crux.” In The Star Atlas Companion: What You Need to Know About the Constellations. Springer Science+Business Media: New York, 2012 (183-7). Located in Google Books Preview [accessed May 1, 2018].

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘Mace Spray’ by The Jezabels off their EP Dark Storm.

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

Ep. 13 Lunar and Solar Orbits - HD and the Void

This is a short one but I do explain concepts you can see and track yourself over the months with very little effort. The shapes of the Moon and how long it takes different planets to orbit the Sun! Time is a human construct! Tidal forces and the ...

Why do the Sun and Moon move the way they do? What’s up with that? Orbits? What? It’s a short but snug little episode here about the Sun and the Moon and how they look from Earth as they zoom across the sky.

Below the cut are my sources, music credits, a vocab list, the transcript of this episode, a composite image of the different phases of the Moon, and a list of the different names for the full moons through the course of a year. Let me know what you think I should research next by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me in real life. And please subscribe to  the podcast on iTunes, rate it or review it, and maybe tell your friends about it if you think they’d like to listen!

(My thoughts on the next episode, because I still haven’t found the time to cover them, are the Voyager golden records, space race history, the transit of Venus, the Moon landing, or Edmond Halley. Let me know by the 6th and I’ll hopefully have the next podcast up on October 16th.)

Glossary

blue moon - when you get two full moons in one calendar month. An older definition is when you get 4 full moons in a season, the third moon is called the ‘blue moon.’

ecliptic - the path of the Sun over the course of a year.

prograde - when a planet spins from east to west. 

retrograde - when a planet spins from west to east.

spaghettification - when extreme tidal forces pull an object apart in space.

Script/Transcript

Sources

Rising and setting times of the Sun on Earth via Cornell University

Seasons on Earth via Cornell University

Lunar phases and the Moon’s relationship to the Sun via Harvard

Tides via Hyperphysics

Tidal forces equation via AstronomyOnline.org

Tidal forces and spaghettification via NASA handout

Lunar phases composite via Fred Espenak

Names of the different full moons throughout the year via EarthSky.org

Blue moons via EarthSky.org

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘See The Constellation’ by They Might Be Giants off their album Apollo 18

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

sun depicted as a divinity petroglyph on the plateau Yagour (High Atlas mountains), Morocco.. 6000 to 8000 BC

Opportunity discovers fresh crater on Mars

via reddit

Light Echoes Used to Study Protoplanetary Disks : This illustration shows a star surrounded by a protoplanetary disk. A new study uses data from NASAs Spitzer Space Telescope and four ground-based telescopes to determine the distance from a star to the inner rim of its surrounding protoplanetary disk. Researchers used a method called photo-reverberation, also known as light echoes.

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Ep. 7 Measuring Mechanisms - HD and the Void

Learn about four ancient (and contemporary, if you work on a ship) devices that utilize very specific areas of astronomy to help you figure out where you are and what time it is, and also predict where celestial bodies will be on other dates and a...

Observing stars is all well and good, but how can I use stars to make my life easier? With a few handy tools and a lot of complicated math and careful table scouting, of course! Okay, it’s not actually any easier to tell where you are, predict when the Sun will rise or where the star Rigel will be at 11:36pm EST, or guess when the next eclipse will be using these tools, but if you don’t have a computer handy maybe it will help.

I did my best to describe all these odd devices in the clearest terms I could but you can hit me up with questions if you have them! Definitely check out some of the video links if you can’t quite picture what I said. I’m also on Twitter at @HDandtheVoid if you’d rather ask me there. And please check out the podcast on iTunes, rate it or review it if you’d like, and subscribe! I’ll always post all the extras here on Tumblr but iTunes is probably more convenient for downloading.

Below the cut are my sources, music credits, vocab list, and the transcript. I mention a play and a story/book and quote an astronomy book in this episode so if you want to see that written down, those sources are there as well. Let me know what you think of this episode, let me know what you think I should research next*, tell me a fun space fact… anything’s helpful!

*(My thoughts were planets, spectroscopy, or Edmond Halley. Let me know by the 6th and I’ll have the next podcast up by July 17th!)

Glossary:

armillary sphere - a device showing the apparent daily motion of the Sun depending on the season, the date, and the latitude of observation. See example video in the link.

Antikythera Mechanism - a device used to establish a calendar based on the Metonic Cycle; eclipse prediction; the location of planets, the Sun, and the Moon on a particular day; and determine the phase of the Moon on a particular day. See example video in the link.

astrolabe - a device for measuring the altitudes of certain celestial objects and for calculating latitude before the development of the sextant. One side is indented, the space called the mater, and can hold a plate depicting the local latitude. Over this plate is a rete, which points out different fixed stars as well as the Sun’s ecliptic, divided into 30 degree sections representing the zodiac signs. On top of the rete was a clock-like hand that stretched the diameter of the astrolabe, called the rule. The rule and rete could be rotated over the face of the plate. See example in the link.

azimuth -  a section of the horizon measured between a fixed point and the vertical circle passing through the center of an object. See example in the link.

declination - the angle of the Sun relative to the equator. The Sun’s angle changes with the seasons.

ecliptic - the path of the Sun over the course of a year.

exeligmos cycle - a cycle that is 3 times the saros cycle, or 669 months. It is more accurate means of predicting eclipses and additionally predicts eclipses that will be visible from a location close to the initial eclipse.

kamal - an Arabic navigation tool consisting of a knotted string and a piece of wood. A navigator would tie a knot in the string and, by holding it in their teeth, sight the North Star along the top of the wooden piece and the horizon along the bottom. To return home, the navigator would sail north or south to bring Polaris to the altitude they had observed in their home port, then turn left or right and sail down the latitude, keeping Polaris at a constant angle. Over time, Arab navigators started tying knots at regular intervals of a fingerwidth, called an issbah, that’s about 1 degree and 36 minutes.

metonic cycle - a 19-year cycle developed by the Babylonians to sync their lunar months with the solar year. In the Metonic cycle, there would be 12 years that lasted 12 lunar months and 7 years that lasted 13 months.

saros cycle - a cycle of 223 months that is used to predict eclipses.

sextant - a device used to determine an observer’s location based on the observation of a known celestial object and a lot of calculation. It is still in use by sailors.

stereographic projection - a process for depicting a spherical, 3-dimensional object on a flat surface. An imaginary line is drawn from one point on the object to a point on the flat surface, following an angle to achieve the same relationship between each point on the object. See example in the link

Script/Transcript

Sources:

Video of how to use an armillary sphere

History of the armillary sphere via University of Cambridge

Video lecture on using an armillary sphere. It sounds like he’s trying to sell it.

Video of how to use an astrolabe

Make your own astrolabe suggestions via In the Sky.org

An old guy kept up a website on astrolabes but he died in April 2016, it’s very sad. Excellent info though.

Explanation of unequal hours

Pullman Car Hiawatha summary, just to prove it’s a real play

Chaucer’s Canterbury Tales with its brief astrolabe mention

Video on how to use a sextant

The many uses of a sextant via Classic Sailing

Why a sextant works via Trailnotes

The history of the sextant

The definition of azimuth

The definition of declination

Video of Antikythera Mechanism’s virtual model based on a theoretical and mechanical model. Just a theoretical model!

Antikythera Mechanism via Smithsonian Magazine

The Antikythera Mechanism Research Project website

Antikythera Mechanism via The New Yorker

Saros cycle via NASA

Saros and Exeligmos cycles

Crouper, Heather and Nigel Henbest. The History of Astronomy. Firefly Books: Buffalo, NY, 2007.

“The circular gear wheels of the Antikythera Mechanism reflect the ancient Greeks’ preoccupation with circles—and with the idea that everything in the sky moves around in circular paths, because the heavens are the home of perfection, and a circle is the ideal shape.” (59)

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘Brooklyn Nights Guitar’ loop from Garageband

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

A teenager designed a pocket-sized satellite that will fly on a NASA mission

An 18-year-old created the world’s lightest functioning satellite, and it’s going to be launched on a real NASA mission next month.

Rifath Sharook, who is from Tamil Nadu, India, made the pocket-sized satellite for a competition called Cubes in Space, which is an international design challenge that asks students aged 11 to 18 to fit their space-worthy invention inside a 13-foot cube.

The pocket-sized 3-D printed satellite is much smaller than that. It weighs just 0.14 pounds and will measure the rotation, acceleration and magnetosphere of Earth, Sharook told Business Standard. Read more (5/17/17)

follow @the-future-now​

10 Things: Mysterious 'Oumuamua

The interstellar object ‘Oumuamua perplexed scientists in October 2017 as it whipped past Earth at an unusually high speed. This mysterious visitor is the first object ever seen in our solar system that is known to have originated elsewhere.  Here are five things we know and five things we don’t know about the first confirmed interstellar object to pass through our solar system.

1. We know it’s not from around here.

 The object known as 1I/2017 U1 (and nicknamed ‘Oumuamua) was traveling too fast (196,000 mph, that’s 54 miles per second or 87.3 kilometers per second) to have originated in our solar system. Comets and asteroids from within our solar system move at a slower speed, typically an average of 12 miles per second (19 kilometers per second) . In non-technical terms, 'Oumuamua is an “interstellar vagabond.”

Artist impression of the interstellar object ‘Oumuamua. Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

2. We’re not sure where it came from.

'Oumuamua entered our solar system from the rough direction of the constellation Lyra, but it’s impossible to tell where it originally came from. Thousands of years ago, when 'Oumuamua started to wander from its parent planetary system, the stars were in a different position so it’s impossible to pinpoint its point of origin. It could have been wandering the galaxy for billions of years.

3. We know it’s out of here.

'Oumuamua is headed back out of our solar system and won’t be coming back. It’s rapidly headed in the direction of the constellation Pegasus and will cross the orbit of Neptune in about four years and cover one light year’s distance in about 11,000 years.

4. We don’t really know what it looks like.

We’ve only seen it as a speck of light through a telescope (it is far away and less than half a mile in length), but its unique rotation leads us to believe that it’s elongated like a cigar, about 10 times longer than it is wide. We can’t see it anymore. Artist’s concepts are the best guesses at what it might look like.

5. We know it got a little speed boost.

A rapid response observing campaign allowed us to watch as 'Oumuamua got an unexpected boost in speed. The acceleration slightly changed its course from earlier predictions.

“This additional subtle force on ′Oumuamua likely is caused by jets of gaseous material expelled from its surface,” said Davide Farnocchia of the Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory. “This same kind of outgassing affects the motion of many comets in our solar system.”

6. We know it’s tumbling.

Unusual variations in the comet’s brightness suggest it is rotating on more than one axis.

This illustration shows ‘Oumuamua racing toward the outskirts of our solar system. As the complex rotation of the object makes it difficult to determine the exact shape, there are many models of what it could look like. Credits: NASA/ESA/STScI

7. We don’t know what it’s made of.

Comets in our solar system kick off lots of dust and gas when they get close to the Sun, but 'Oumuamua did not, which led observers to consider defining it as an asteroid.

Karen Meech, an astronomer at the University of Hawaii’s Institute of Astronomy, said small dust grains, present on the surface of most comets, may have eroded away during ′Oumuamua’s long journey through interstellar space. “The more we study ′Oumuamua, the more exciting it gets.” she said. It could be giving off gases that are harder to see than dust, but it’s impossible to know at this point.

8. We knew to expect it.

Just not when. The discovery of an interstellar object has been anticipated for decades. The space between the stars probably has billions and billions of asteroids and comets roaming around independently. Scientists understood that inevitably, some of these small bodies would enter our own solar system. This interstellar visit by ‘Oumuamua reinforces our models of how planetary systems form.

9. We don’t know what it’s doing now.

After January 2018, ’Oumuamua was no longer visible to telescopes, even in space. But scientists continue to analyze the data gathered during the international observing campaign and crack open more mysteries about this unique interstellar visitor.

10. We know there’s a good chance we’ll see another one…eventually.

Because ′Oumuamua is the first interstellar object ever observed in our solar system, researchers caution that it’s difficult to draw general conclusions about this newly-discovered class of celestial bodies. Observations point to the possibility that other star systems regularly eject small comet-like objects and there should be more of them drifting among the stars. Future ground- and space-based surveys could detect more of these interstellar vagabonds, providing a larger sample for scientists to analyze. Adds, Karen Meech, an astronomer at the University of Hawaii’s Institute of Astronomy: “I can hardly wait for the next interstellar object!“

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

I just watched the 4 clearly visible planets march across the sky with the moon in the center, so here’s a short guide to the night sky as the last 3 move across.

mammenxTime lapse of the milky way rolling across the night sky, flanked by the planets Jupiter, Saturn & Mars. Taken from Diskit Ladakh, this place truly has some fantastic unobstructed views of the night sky

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