TELLURIAN

This is a Trichroic Beam Splitter.

Using this splitter a white beam of light can be separated into three colours. Red, Blue and Green.

Source

Bright Spiral Galaxy M81 : One of the brightest galaxies in planet Earths sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy can be found toward the northern constellation of the Great Bear . This superbly detailed view reveals M81s bright yellow nucleus, blue spiral arms, and sweeping cosmic dust lanes with a scale comparable to the Milky Way. Hinting at a disorderly past, a remarkable dust lane actually runs straight through the disk, to the left of the galactic center, contrary to M81s other prominent spiral features. The errant dust lane may be the lingering result of a close encounter between M81 and its smaller companion galaxy, M82. Scrutiny of variable stars in M81 has yielded one of the best determined distances for an external galaxy 11.8 million light-years. via NASA

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Escape velocities for every planet in the solar system

Ep. 21 Radio Astronomy and RQZs - HD and the Void

Be brave in the face of an extremely technical episode where I tackle radio astronomy! Astronomers collect radio waves to map distant objects. To do their work they need a level of quiet that's hard to find without some help from Radio Frequency I...

I’ve gotten some feedback that episodes can be too technical. Unfortunately, that feedback came too late to save you from this week’s episode, which requires me to summarize the electromagnetic spectrum, radio astronomy, a concept called interferometry, and government regulations to talk about the topic that originally started me on this path: radio quiet zones. Please, bear with me! Pardon my mess! It was all very interesting stuff, I couldn’t resist digging into it.

Below the cut are my sources, music credits, a vocab list, a timeline of the astronomers I mention, and the transcript of this episode. I’ve bolded those sources I mention in the podcast, including the podcast that started me on this topic: The Adventure Zone! Please 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. I’d love it if you would subscribe on iTunes, rate my humble little podcast and maybe review it, and tell friends if you think they’d like to hear it!

(My thoughts on the next episode are SOFIA, which you need to listen to find out what it stands for, or the pilot Chuck Yaeger. The next episode will go up February 26th.)

Glossary

aperture synthesis - the process of collecting electromagnetic radiation from a variety of separate, small telescopes and then combining this data to recreate the image at a higher resolution than would be possible with a single telescope.

frequency - the number of times a wave oscillates up and down per second.

hertz - the number of times an electromagnetic wave cycles per second. One cycle per second is 1 hertz.

interferometry - a group of techniques to extract information from superimposing electromagnetic waves to create interference. In radio astronomy, this is done by using a wide spread of receivers to look at the same distant object, then bringing that data together with a correlator that can create a larger, clearer picture than an individual radio telescope alone could.

radiation - energy that travels and spreads out as it goes.

Script/Transcript

Timeline

Joseph-Louis Lagrange, French (1736-1813)

Armand-Hippolyte-Louis Fizeau, French (1819-1896)

Edward W. Morley, American (1838-1923)

Albert A. Michelson, American (1852-1931)

Sir Martin Ryle, British (1918-1984)

Bernard Yarnton Mills, Australian (1920-2011)

Derek Vonberg, British (1922-2015)

Antony Hewish, British (1924- )

Sources

Electromagnetic spectrum via NASA

Observatories across the EM spectrum via NASA

Fermi satellite via NASA

The Neil Gehrels Swift Observatory via NASA

NuSTAR via Caltech

NuSTAR via NASA

Chandra X-Ray Observatory via Harvard

The Galaxy Evolution Explorer (GALEX) via Caltech

Kepler satellite via NASA

Hubble Space Telescope via NASA

Spitzer satellite via Caltech

Stratospheric Observatory for Infrared Astronomy (SOFIA)

Planck satellite via ESA

Spekt-R Radioastron from Russia

High Energy Stereoscopic System (HESS)

W. M. Keck Observatory on Mauna Kea

South Africa Large Telescope (SALT) in Namibia

The Combined Array for Research in Millimeter-Wave Astronomy (CARMA) via Caltech

CARMA public page (decommissioned)

Very Large Array (VLA) via NRAO

Space radio telescope (1997) via NRAO

Highly Advanced Laboratory for Communications and Astronomy (HALCA) via NASA

A timeline of the history of radio interferometry via University of Groningen (Netherlands)

Interferometers via the LIGO Laboratory

Michelson-Morley Experiment via University of Virginia

Astronomical Interferometry via Magdalena Ridge Observatory

Interferometry via XKCD

How Radio Works via How Stuff Works

Radio Spectrum Allocation via the Federal Communications Commission

Interferometry via the European Space Observatory

National Radio Quiet Zone via National Radio Astronomy Observatory

“minimize possible harmful interference to the National Radio Astronomy Observatory (NRAO) in Green Bank, WV and the radio receiving facilities for the United States Navy in Sugar Grove, WV.”

National Radio Quiet Zone via CNN

“Tucked in the Allegheny Mountains, researchers are listening to exploding galaxies at the edge of the universe – a signal that is so faint, it’s about a billionth of a billionth of a millionth of a watt.”

The Quiet Zone: Where mobile phones are banned via BBC News (May 2015)

Enter The Quiet Zone: Where Cell Service, Wi-Fi Are Banned via NPR (Oct 2013)

Green Bank Observatory in West Virginia, USA

Karen O’Neil: “The types of energies we look at are less than the energy of a single snowflake falling on the Earth.”

Characteristics of radio quiet zones via International Telecommunication Union (Sept 2012)

“transmissions below 15 GHz are restricted within a certain radius around the Arecibo Observatory, located in Puerto Rico. Since no observations are carried out, nor are any expected to be carried out above that frequency in the future, no restrictions are needed on higher frequency transmissions. The reverse is not necessarily true, however. For example, some restrictions may be imposed on transmissions below 30 GHz in the neighbourhood of the large international ALMA observatory even though it is not expected to ever observe below that frequency, due to its susceptibility to interference at these lower frequencies in the signal path.”

“It is important to emphasize that a RQZ does not imply a complete absence of radio transmissions. The existence of, and coexistence with, a range of man-made devices will always be necessary. A RQZ may include options for notification of other users and for negotiation in mitigating interference. On the other hand, a RQZ does not consist entirely of mitigating techniques implemented by the radio astronomy facility; some level of control on externally-generated interference is intrinsic to a RQZ.

A RQZ is therefore a buffer zone that allows for the implementation of mechanisms to protect radio astronomy observations at a facility within the zone from detrimental radio frequency interference, through effective mitigation strategies and regulation of radio frequency transmitters.”

ALMA Observatory website

The Scientific Committee on Frequency Allocations for Radio Astronomy (IUCAF) website

Google Map of worldwide radio quiet zones (Aug 2016)

ITU-R Recommendations of Particular Importance to Radio Astronomy by A. Richard Thompson

“the necessity of maintaining the shielded zone of the Moon as an area of great potential for observations by the radio astronomy service and by passive space research, and consequently of maintaining it as free as possible from transmissions.”

The Adventure Zone: Amnesty setup episode via Maximum Fun

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

Filler Music: ‘Junkyard Chandelier’ by Radical Face aka Ben Cooper, who primarily releases music as Radical Face but also has at least three other bands or band names he’s working with/has released music as.

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

September 15

This one is technically not yet history, because at the time of posting, the little craft has about half an hour left to go.  That said, let’s proceed.

In 2017, NASA’s Cassini space probe ended its twenty-year mission at Saturn.  After a nearly-seven-year-long journey there, it orbited the ringed planet for 13 years and just over two months, gathering copious amounts of information about the planet, said rings, and many of its moons.  It landed an ESA probe called Huygens on Titan, the first-ever soft landing in the outer Solar System.  It discovered lakes, seas, and rivers of methane on Titan, geysers of water erupting from Enceladus (and passed within 50 miles of that moon’s surface), and found gigantic, raging hurricanes at both of Saturn’s poles.  

And the images it returned are beautiful enough to make you weep.

On this day in 2017, with the fuel for Cassini’s directional thrusters running low, the probe was de-orbited into the Saturnian atmosphere to prevent any possibility of any contamination of possible biotic environments on Titan or Enceladus.  The remaining thruster fuel was used to keep the radio dish pointed towards Earth so the probe could transmit information about the upper atmosphere of Saturn while it was burning up due to atmospheric friction.

This is us at our best.  We spent no small amount of money on a nuclear-powered robot, launched it into space, sent it a billion miles away, and worked with it for two decades just to learn about another planet.  And when the repeatedly-extended missions were through, we made the little craft sacrifice itself like a samurai, performing its duty as long as it could while it became a shooting star in the Saturnian sky.

Rhea occulting Saturn

Water geysers on Enceladus

Strange Iapetus

Look at this gorgeousness

A gigantic motherfucking storm in Saturn’s northern hemisphere

Tethys

This image is from the surface of a moon of a planet at least 746 million miles away.  Sweet lord

Mimas

Vertical structures in the rings.  Holy shit

Titan and Dione occulting Saturn, rings visible

Little Daphnis making gravitational ripples in the rings

That’s here.  That’s home.  That’s all of us that ever lived.

Saturn, backlit

A polar vortex on the gas giant

Icy Enceladus

(All images from NASA/JPL)

Just a reminder that the first NASA astronauts were supposed to be women because generally they are smaller, lighter (less weight in the cockpit means less fuel required) and eat less than men and so would be easier to accommodate in space. 

Sharpest View of the Andromeda Galaxy, Ever.

The NASA/ESA Hubble Space Telescope has captured the sharpest and biggest image ever taken of the Andromeda galaxy — a whopping 69,536 x 22,230 pixels. The enormous image is the biggest Hubble image ever released and shows over 100 million stars and thousands of star clusters embedded in a section of the galaxy’s pancake-shaped disc stretching across over 40,000 light-years.

Use the ZOOM TOOL to view in full detail.

(WARNING: May cause existential crisis)

I still highly recommend this good, beautiful web comic about love in space, and now it's all done! You can read it all.

The final three chapters are up. Read it now. 

That’s it folks, On A Sunbeam is over. Though I am pondering a sequel. 

Thank you all so much for following along. 

Ep. 31 Astrogeology - HD and the Void

There is a branch of study where rocks and space meet (sometimes to explosive effect, when asteroids and meteorites are concerned)... It can be called planetary geology, exogeology, or astrogeology. Listen to hear more about what the life of an as...

New Zealand was lovely, but I already touched on what I’d be tempted to talk about with my Southern Stars episode. A person I interviewed as a potential new housemate gave me the idea for this episode because the joy of outer space is truly everywhere and anywhere. The field of astrogeology was not something I had heard of before, though I had indirectly heard of Eugene Shoemaker. I knew the comet Shoemaker-Levy 9 was named after him (and Carolyn Shoemaker, his wife). It turns out he basically founded the modern field of astrogeology! So I talk about him for quite a while, too.

Below the cut are the glossary, transcript, sources, and music credits. Send me any topic suggestions via Tumblr message (you don’t need an account to do this, just submit as anonymous). You can also tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me in real life. Subscribe on iTunes to get the new episodes of my semi-monthly podcast, and please please please rate and review it. Go ahead and tell friends if you think they’d like to hear it, too!

(The next episode is going to be famous comets, and I’m shooting for an April release.)

Glossary

aeolian processes - the wind’s ability to shape the surface of a planet by eroding, transporting, and depositing materials. Most effective in desert regions, where the sparse vegetation, dry soil, and loose sediments mean these processes have the greatest impact.

albedo features -  the International Astronomical Union term for an area of a planet that has a high contrast in color with the surrounding area on a planet’s surface.

chaos terrain - the International Astronomical Union term for where ridges, cracks, and plains on a planet’s surface appear broken and smashed up against each other.

chasma - the International Astronomical Union term for a long, steep-sided, deep surface indentation in a planet’s surface.

colles - the International Astronomical Union term for collections of small, knob-like hills on the surface of a planet.

dorsum - the International Astronomical Union term for a wrinkle-like ridge on a planet’s surface.

facula -  the International Astronomical Union term for a bright spot on planets or moons.

fluvial processes - the ways in which rivers and streams impact a planet’s surface by eroding or creating deposits and landforms out of sediment. Sometimes, streams or rivers are associated with glaciers, ice sheets, or ice caps, and then they are called glaciofluvial or fluvioglacial processes.

fossa - the International Astronomical Union term for a long, narrow depression in a planet’s surface.

lacunae - the International Astronomical Union term for irregularly shaped depressions that look like dry lake beds on the surface of Saturn’s moon, Titan.

lobate scarp - the International Astronomical Union term for a curved slope that is probably formed by compressive tectonic movement.

mare - the International Astronomical Union term for a large, circular plain on a planet’s surface.

terra - the International Astronomical Union term for an extensive landmass like a plain or highland.

tesserae - the International Astronomical Union term for regions on the planet Venus that are tiled, polygonal shapes.

vallis - the International Astronomical Union term for a valley on the surface of a planet.

Script/Transcript

Sources

Planetary geology via Wikipedia

Lunar Lobate Scarp via the Lunar Reconnaissance Orbiter Camera

Eugene M. Shoemaker Biographical Memoirs via NASA

Dr. Eugene Shoemaker, 69; Set Record for Finding Comets via The New York Times (July 1997)

Eugene Shoemaker (1928-1997) via NASA Jet Propulsion Lab

Eugene Shoemaker (1928 - 1997) via American Astronomical Society

Gene Shoemaker - Founder of Astrogeology via US Geological Society

Eugene Shoemaker via the Planetary Society

Eugene Shoemaker Ashes Carried on Lunar Prospector via NASA Jet Propulsion Lab

Eugene M. Shoemaker and the Integration of Earth and Sky via GSA Today (April 2001)

Destination Moon by Carolyn C. Porco (Feb 2000)

“I wanted to include something to commemorate Gene’s scientific legacy. It seemed appropriate to choose his favorite photo of Meteor Crater and a photo of the last comet that he and his wife saw together, Comet Hale-Bopp. And somehow, I extracted from the dusty realm of dim memory a passage I had read from Romeo and Juliet long ago that seemed perfect for the occasion.”

Who is an Astrogeologist? via Space Awareness

Careers via the USGS Astrogeology Science Center

“Public Service by contributing to the public knowledge about our Solar System.”

Lunar Calibration via USGS

“The unmatched stability of the lunar surface reflectance (better than one part in 108 per year) makes the Moon attractive as a calibration light source; its radiance can be known with high precision and accuracy. The lunar irradiance is similar in brightness to sunlit land masses on the Earth.”

Video: Astrogeology 1963-2013: Fifty Years of Exploration via the USGS Astrogeology Science Center

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

Filler Music: ‘Muddy Waters’ by LP off her album Lost On You

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

If Earth had Saturn’s Rings

From an excellent post by Jason Davis

From Washington, D.C., the rings would only fill a portion of the sky, but appear striking nonetheless. Here, we see them at sunrise.

From Guatemala, only 14 degrees above the equator, the rings would begin to stretch across the horizon. Their reflected light would make the moon much brighter.

From Earth’s equator, Saturn’s rings would be viewed edge-on, appearing as a thin, bright line bisecting the sky.

At the March and September equinoxes, the Sun would be positioned directly over the rings, casting a dramatic shadow at the equator.

At midnight at the Tropic of Capricorn, which sits at 23 degrees south latitude, the Earth casts a shadow over the middle of the rings, while the outer portions remain lit.

via x