Glossary

Of Course I Still Love You returned to Port Canaveral earlier this morning with the SES-10 Falcon 9 first stage. Since this is the first Falcon 9 rocket to be reflown this marks the second time this particular rocket returned to port after landing. The images above were captured by remote cameras on the droneship and show the vehicle coming into land. Falcon 9 landed eight minutes after a March 30 liftoff from LC-39A at Kennedy Space Center. Extensive scorching is visible on the exterior of the rocket including the interstage and grid fins. The fins themselves were seen glowing during launch footage as the booster returned to Earth. Each fin is coated in ablative paint which helps protect the metal but the severe temperatures of reentry still cause the fins to glow. Since SES-10 was placed into Geostationary Transfer Orbit, not enough propellant remained in the first stage’s tanks to allow for a nominal reentry profile and the boostback burn was not performed. As such, the rocket came in over twice its normal landing speed and eight times hotter than flights which have a boostback burn. This particular rocket will not be reused after recovery; Elon Musk stated in the SES-10 post-launch news conference that the rocket will likely be given to the Air Force for display at either Cape Canaveral or Kennedy Space Center. P/C: SpaceX

New Horizons Flyover of Pluto

Using actual New Horizons data and digital elevation models of Pluto and its largest moon Charon, mission scientists have created flyover movies that offer spectacular new perspectives of the many unusual features that were discovered and which have reshaped our views of the Pluto system – from a vantage point even closer than the spacecraft itself. This dramatic Pluto flyover begins over the highlands to the southwest of the great expanse of nitrogen ice plain informally named Sputnik Planitia. The viewer first passes over the western margin of Sputnik, where it borders the dark, cratered terrain of Cthulhu Macula, with the blocky mountain ranges located within the plains seen on the right. The tour moves north past the rugged and fractured highlands of Voyager Terra and then turns southward over Pioneer Terra – which exhibits deep and wide pits – before concluding over the bladed terrain of Tartarus Dorsa in the far east of the encounter hemisphere. Digital mapping and rendering were performed by Paul Schenk and John Blackwell of the Lunar and Planetary Institute in Houston.

ASTROVAGANT

[adjective]

travelling through space; traverse through stars.

Etymology: from Greek astron, “stars” + Latin vagans, past participle of vagary, “to wander about”.

Ep. 5 Star Classifications Part 1: Leavitt and Variable Stars - HD and the Void

First in a two-part series about stars and how we classify them. Variables are a very specific kind of star that have a regular variation in brightness, like a heartbeat. They were first categorized and analyzed by Henrietta Swan Leavitt at the tu...

Stars are too distant to really peer at and they have all that radiation and heat and blinding light and such so it’s doubtful that we will ever be able to prod the Sun, but astronomers can certainly classify what stars we’ve been able to observe! This is the first part of a two-part series on star classification systems. This podcast focuses on variable stars, how they were discovered, the awesome women who started developing the basis of a major star classification system, and what variable stars did for our understanding of the universe. 

There is a lot of technical talk and I did my best to make it comprehensible but you can absolutely hit me up with questions if you have them! I’m also on Twitter at @HDandtheVoid if you’d rather ask me there. And go ahead and 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 might be more convenient for downloading and podcast apps and all that good stuff.

Below the cut is some elaboration on the episode itself, including my sources, music credits, a BIG glossary, a quote on women and emotional labor that really hits home for me, and a transcript. I mention a couple of books and quote a couple people 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! 

*(The June 19th podcast is already set, it’s going to be part 2 on star classifications, but in July I could start talking about things like spectroscopy, planets, dark matter, or I have a book in at the library on longitude.)

Glossary:

arcsecond - an infinitesimal measurement of a degree; in 1 degree there are 3,600 arcseconds.

cosmic distance measurements: light-years - a way to imagine distance scales on an astronomical level; the distance light can travel in one year, or about 6 trillion miles. parsecs - a measurement of distance on an astronomical scale; the distance to a star that shifts by one arcsecond from one side of Earth’s orbit to the other. It’s more common than using light-years when discussing deep space astronomy. One parsec is about 19 trillion miles (30 trillion kilometers), a bit over 3 light-years.

magnitude - the measurement of a star’s brightness as seen from earth. The brighter it is, the lower its magnitude value; the Sun has an apparent magnitude of -27.

Malmquist Bias - the stars that are visible in a cluster are the brightest ones. Astronomers rely on them to compute average luminosity, but the fact that they’re the brightest ones inevitably skews the results.

parallax - the apparent shift of an object when viewed through two different lines of sight.

radial velocity - the speed at which a star is moving away from or towards Earth.

standard candle - a kind of celestial object that has a known luminosity due to some characteristic that the entire class of objects possesses.

stellar photometry - measuring and recording the magnitude of stars.

triangulation - a technique to measure the distance of an object by observing it from two different locations, knowing the distance between both observation locations and measuring the angle at which the distant object moves (its parallax angle).

variable stars: variable stars - stars that change brightness. Reasons for the brightness changes vary, and certain types of variable stars can be used to determine relative distance. They are either intrinsic (when a change in brightness is caused by a star’s own physical changes, like pulsation or eruption) or extrinsic (when the variance has an external cause, such as an eclipse of one star by another or stellar rotation). Cepheid variables - variable stars with a period between 1 and 70 days, with light variations from 0.1 to 2 magnitudes. They’re massive, with a high luminosity and are usually classified between F and G or K. They obey the period-luminosity relationship and played a major part in calculating distances to far-away galaxies as well as helping to determine the age of the Universe. eclipsing binaries - binary systems of stars where the components regularly eclipse one another, causing an apparent decrease in the brightness of the system. irregular variables - variable stars, typically red giants, without a measurable period to their luminosity. Long Period Variables - LPVs have periods ranging from 30 to 1,000 days. They’re red giants or supergiants, typically classified M, R, C, or N. There are subclasses, too: Mira, which have light variations of more than 2.5 magnitudes and are the future evolution of our own star, the Sun; and semiregular, which have some regular periods and some irregular light variation and have light variations less than 2.5 magnitudes. RR Lyrae - variable stars with a period of 0.05 to 1.2 days and a light variation between 0.3 and 2 magnitudes. They’re older and smaller than Cepheids, and are white giant stars typically classified as A. RV Tauri - variable stars that have periods between 30 and 150 days, light variation up to 3 magnitudes, and possible cycle variations that can be hundreds or thousands of days long. They’re yellow supergiants classified between G and K.

cataclysmic variables: dwarf nova - a close binary system of a red dwarf, a white dwarf, and an accretion disk around the white dwarf. They brighten by 2 to 6 magnitudes depending on the stability of the disk, which loses material to the white dwarf. nova - a close binary system of a white dwarf and a secondary star that’s a little cooler than the Sun. The system brightens 7 to 16 magnitudes in 1 to 100 days, and then the star fades slowly to the initial brightness over a period of several years or decades. At maximum brightness, it’s similar to an A or F giant star. Recurrent novae are similar to this category of variable but have several outbursts during their recorded history. R Coronae Borealis - an eruptive variable, a supergiant star that is hydrogen-poor and carbon-rich and spends most of its time at maximum light, fading as much as 9 magnitudes at irregular intervals. Most often classified between F and K or R. supernova - a massive star that explodes with a magnitude increase of 20 or more. Supernovae have led us to realize that the expansion of the Universe is accelerating. symbiotic stars -  close binary systems of a red giant and a hot blue star. They have nova-like outbursts up to 3 magnitudes.

Script/Transcript

Sources:

What stars are made of via NASA

Stars, Cepheid Variable by T. Lloyd Evans via the California Institute of Technology aka CalTech

Variable stars via the Australia Telescope National Facility

American Association of Variable Star Observers website. I used a couple of pages from this one but the whole organization is kinda on the nose.

Stellar magnitude via EarthSky

A star magnitude scale via Harvard

Harvard Observatory’s Astronomical Photographic Plate Collection, which has a history of the collection and the women computers.

Definitions and differences for parsecs and light-years, and a description of parallax and triangulation via EarthSky

Standard candle breakdowns via some magical wonderful person with the best accessible online science book project I have ever encountered. Mad props to whoever is doing this, it’s a noble cause.

Info on Walter Baade via the Online Archives of California

A very math-y breakdown of the Malmquist Bias in the article “Observational Selection Bias Affecting the Determination of the Extragalactic Distance Scale” by P. Teerikorpi, published 1997

Johnson, George. Miss Leavitt’s Stars. Atlas Books: NY, 2005.

Henrietta Swan Leavitt quote: “It is worthy of notice [that] the brighter variables have the longer periods” (38).

“If a theory or observation seemed to suggest that we, the observers, happen to occupy an exalted place in the heavens, then it was probably wrong” (110)

Edwin Hubble quote: “With increasing distance, our knowledge fades, and fades rapidly. Eventually, we reach the dim boundary—the utmost limits of our telescopes. There, we measure shadows, and search among ghostly errors of measurements for landmarks that are scarcely more substantial” (130)

Pickover, Clifford A. “Leavitt’s Luminosity Law.” Archimedes to Hawking: Laws of Science and the Great Minds Behind Them. Oxford UP: NY, 2008. 475.

Soba, Dava. The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars. Viking: New York, 2016.

From Claire Messud’s The Woman Upstairs (I haven’t read the book, I just collect quotes, so this isn’t me endorsing the book; I know nothing about it except this paragraph): “I’m a good girl, I’m a nice girl, I’m a straight-A, strait-laced, good daughter, good career girl, and I never stole anybody’s boyfriend and I never ran out on a girlfriend, and I put up with my parents’ shit and my brother’s shit, and I’m not a girl anyhow, I’m over forty fucking years old, and I’m good at my job and I’m great with kids and I held my mother’s hand when she died, after four years of holding her hand while she was dying and I speak to my father every day on the telephone–every day, mind you, and what kind of weather do you have on your side of the river, because here it’s pretty gray and a bit muggy too? It was supposed to say ‘Great Artist’ on my tombstone, but if I died right now it would say ‘such a good teacher/daughter/friend’ instead; and what I really want to shout, and want in big letters on that grave, too, is FUCK YOU ALL.”

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

Filler Music: 'River Man’ by Nick Drake off his album Five Leaves Left.

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

Ep. 14 Dark Matter Part 1 - HD and the Void

In preparation for a future interview with someone who knows much more about astroparticle physics and dark matter than I do, tune in this week for a quick-and-dirty breakdown of a theoretical particle that, if it exists, would clarify a couple of...

We’re getting theoretical here, and not just astronomy theory but particle theory. That’s right, it’s a dark matter podcast! Learn what some astronomers think it is and why other astronomers think there are better explanations for certain nutty galactic phenomena. Hear about MACHOs and WIMPs! Also learn what dark matter is too hot, too cold, too medium, or just right! 

Below the cut are my sources, music credits, a vocab list, a timeline of the scientists I mention, and the transcript of this episode. Tell me 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 and maybe review it, and tell friends if you think they’d like to listen!

(There’s a lot of ever-evolving info about dark matter and I was not able to cover all of it in just one episode, so get excited to hear about dark matter’s friend, dark energy, on November 6th. My thoughts on the episode after that are still the Voyager golden records, space race history, the transit of Venus, the Moon landing, or Edmond Halley. Let me know what you think!)

Glossary

astroparticle physics - the interface between astrophysics and particle physics.

baryons - heaviest particles. Ex. Protons, neutrons. In astroparticle physics, electrons are included in baryonic matter.

bosons - particles that can exist in the same state at the same location at the same time. Ex. Photons, Higgs boson.

cosmic microwave background radiation - the electromagnetic radiation left over from the time of recombination in Big Bang cosmology.

dark matter - a theoretical mass made up of unknown particles that have not been created on Earth. It is used to explain why galaxy clusters have 10x the mass that their light output suggests they would have; why distant stars on the edges of spiral galaxies orbit at the same speed as stars near the center of the galaxy; and the accretion of gases that created galaxies at the beginning of the universe.

fermions - particles that cannot exist in the same state at the same location at the same time. Ex. Protons, neutrons, electrons, leptons.

gravitational lensing - when light from more distant sources passes near a massive star, galaxy, or galaxy cluster and the object’s gravity bends the light like a lens to provide a warped angle view of space.

leptons - lightest particles. Ex. Electrons, neutrinos, tau particles, muons.

MACHO - acronym for MAssive Compact Halo Object. Made of baryonic matter, these objects are a theoretical explanation that takes the place of dark matter and include neutron stars, black holes, or brown dwarfs.

mesons - medium-weight particles. Ex. Pions, kaons.

Planck satellite - a spacecraft that operated from 2009 to 2012. It measured the dark matter content of the universe by looking at the cosmic microwave background radiation and seeing how dark matter clumped and drew the regular matter together to form galaxies.

WIMP - acronym for Weakly Interacting Massive Particle. Theoretical particles that can pass through ordinary matter without affecting it.

Wilkinson Microwave Anisotropy Probe - a spacecraft operating from 2001 to 2010 which measured temperature differences in the cosmic microwave background radiation leftover from the Big Bang.

Transcript

Sources

Fritz Zwicky via the Swedish Morphological Society

Fritz Zwicky via the American Museum of Natural History

Zwicky: “Astronomers are spherical bastards. No matter how you look at them they are just bastards“

Vera Rubin via the American Museum of Natural History

Vera Rubin via Astronomy Magazine

Morton Roberts’ 2007 article on dark matter via Harvard

Particle classifications via PhysicsNet.co.uk

Leptons via Georgia State University, copyright 2001 and all written by Carl “Rod” Nave, who has a teaching award named after him at GSU. Go Rod!

Fermions and bosons via The Particle Adventure

MOND theory by Mordehai Milgrom, published in Scientific American Aug. 2002

Newton’s Second Law of Motion via NASA

MACHOs and WIMPs via NASA

MACHOs and WIMPs via the Encyclopedia of Astronomy and Astrophysics

Bertone, Gianfranco. Behind the Scenes of the Universe: From the Higgs to Dark Matter. Oxford U P: Oxford, 2013.

Tucker, Wallace H. Chandra’s Cosmos: Dark Matter, Black Holes, and Other Wonders Revealed by NASA’s Premier X-Ray Observatory. Smithsonian Books: Washington, D.C, 2017.

“a mysterious force that causes the observed accelerating expansion of the universe” (3).

“sterile neutrinos, axions, asymmetric dark matter, mirror dark matters, and extradimensional dark matter” (23).

“the concentration of dark matter is leveling off, rather than peaking sharply, in the central regions of this cluster” (31).

Timeline

Albert Einstein, German/Austrian (1879-1955)

Edwin Hubble, American (1889-1953)

Walter Baade, German (1893-1960)

Fritz Zwicky, Swiss (1898-1974)

Enrico Fermi, Italian (1901-1954)

Morton S. Roberts, American (1926- )

Vera Rubin, American (1928-2016)

Peter Higgs, English (1929- )

Kent Ford, American (1931- )

Mordehai Milgrom, Israeli (1946- )

Romeel Dave

Rachel Somerville

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

Filler Music: ‘Darkmatter’ by Andrew Bird off his album Fingerlings 3

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

Cassini's Final Image of Saturn

Here's a mosaic of Saturn made from raw images acquired by Cassini on Sept. 13, 2017, as it was on its way toward its dive into the planet's atmosphere. These images are uncalibrated for color but were acquired in visible-light RGB filters. This will be our last close-up image of Saturn for a long time. Credit: NASA/JPL-Caltech/Space Science Institute/Jason Major

The last look before her descent in fire…

I talked about Proxima Centauri last week but didn't realize it has a planet!

It’s starry scholastic month! Planet X will start it off with his first lesson: Proxima B!

http://www.space.com/33845-why-proxima-b-exoplanet-hard-to-find.html

This photo of Astronaut Charlie Duke’s family has been on the moon for the last 43 years.

via reddit

Why Star Trek matters.

Biggest Scientific Breakthroughs of 2013

From intergalactic neutrinos and invisible brains, to the creation of miniature human “organoids”, 2013 was an remarkable year for scientific discovery. Here are some of the biggest scientific breakthroughs, innovations and advances of 2013.

Voyager I Leaves the Solar System

Escaping the solar system is no mean feat. For 36 years, NASA’s Voyager 1 spacecraft has putting distance between itself and the Sun at speeds approaching 11 miles per second. At a pace like that, scientists knew Voyager was approaching the fringes of the heliosphere that surrounds and defines our solar neighborhood – but when would it break that barrier? When would it make the leap to interstellar space? After months of uncertainty, NASA finally made the news official this September. “Voyager 1 is the first human-made object to make it into interstellar space” said Don Gurnett, lead author of the paper announcing Voyager’s departure; “we’re actually out there.”

The Milky Way is Brimming with Habitable Worlds

Planet-hunting scientists announced in November that 22% of sunlike stars in the Milky Way are orbited by potentially habitable, Earth-size worlds. This remarkable finding suggests there could be as many as two-billion planets in our galaxy suitable for life — and that the nearest such planet may be only 12 light-years away. Is Earth 2.0 out there? With figures like that, it’s hard to imagine otherwise. Who knows – with all the Kepler data we’ve got to sift through, there’s a chance we’ve already found it. 

Curiosity Confirms Mars Was Once Capable of Harboring Life

In March, NASA scientists released perhaps the most compelling evidence to date that the Red Planet was once capable of harboring life. Earlier this year, Curiosity drilled some samples out of a sedimentary rock near an old river bed in Gale Crater. This geological area used to feature a series of stream channels, leaving behind finely grained bedrock indicative of previously wet conditions. Using the rover’s onboard instrumentation, NASA scientists analyzed these samples to detect some of the critical elements required for life, including sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon. The rover is currently on a trek to its primary scientific target – a three-mile-high peak at the center of Gale Crater named Mount Sharp – where it will attempt to further reinforce its findings.

Researchers Detect Neutrinos from Another Galaxy

By drilling a 1.5 mile hole deep into an Antarctic glacier, physicists working at the IceCube South Pole Observatory this year captured 28 neutrinos, those mysterious and extremely powerful subatomic particles that can pass straight through solid matter. And here’s the real kicker: the particles likely originated from beyond our solar system – and possibly even our galaxy. "This is a landmark discovery,“ said Alexander Kusenko, a UCLA astroparticle physicist who was not involved in the investigation, "possibly a Nobel Prize in the making.”

NASA Discovers “A Previously Unknown Surprise Circling Earth”

NASA’s recently deployed Van Allen probes — a pair of robotic spacecraft launched in August 2012 to investigate Earth’s eponymous pair of radiation belts — turned out out some very unexpected findings in February, when they spotted an ephemeral third ring of radiation, previously unknown to science, surrounding our planet.

Human Cloning Becomes a Reality

A scientific milestone 17 years in the making, researchers announced in May that they had derived stem cells from cloned human embryos.The controversial technology could lead to new treatments for diseases like Parkinson’s and diabetes — while bringing us one step closer to human reproductive cloning.

Giant “Pandoravirus” Could Redefine Life as we Know it

Scientists in July announced the discovery of a pair of viruses that defy classification. Bigger and more genetically complex than any viral genus known to science, these so-called “pandoraviruses” could reignite a longstanding debate over the classification of life itself.

Brain-to-Brain Interfaces Have Arrived

Back in February, researchers announced that they had successfully established an electronic link between the brains of two rats, and demonstrated that signals from the mind of one could help the second solve basic puzzles in real time — even when those animals were separated by thousands of miles. A few months later, a similar connection was established between the brain of a human and a rat. Just one month later, researchers published the results of the first successful human-to-human brain interface. The age of the mind-meld, it seems, is near at hand.

There is Life at the End of the World

There is life in Lake Whillans. For millions of years, the small body of liquid water has lurked hundreds of meters below Antarctica’s Ross Ice Shelf, sealed off from the outside world and the scientists who would explore its subglacial depths. Earlier this year, a team of researchers led by Montana State University glaciologist John Priscu successfully bored a tunnel to Whillans and encountered life, making Priscu and his colleagues the first people in history to discover living organisms in the alien lakes at the bottom of the world.

Doctors Cure HIV in a Baby Born With the Disease

In a monumental first for medicine, doctors announced in March that a baby had been cured of an HIV infection. Dr. Deborah Persaud, who presented the child’s case at the 20th annual Conference on Retroviruses and Opportunistic Infection, called it “definitely a game-changer.”

Newly Discovered Skulls Could Prune Humans’ Evolutionary Tree

An incredibly well-preserved, 1.8-million-year-old skull from Dmanisi, Georgia suggests the evolutionary tree of the genus Homo may have fewer branches than previously believed. In a report published in October, a team led by Georgian anthropologist David Lordkipanidze writes that it is “the world’s first completely preserved hominid skull.” And what a skull it is. When considered alongside four other skulls discovered nearby, it suggests that the earliest known members of the Homo genus (H. habilis, H.rudolfensis and H. erectus) may not have been distinct, coexisting species, at all. Instead, they may have been part of a single, evolving lineage that eventually gave rise to modern humans.

Neuroscientists Turn Brains Invisible

Gaze upon the stunning effects of CLARITY, a new technique that enables scientists to turn brain matter and other tissues completely transparent. It’s been hailed as one of the most important advances for neuroanatomy in decades, and it’s not hard to see why.

[source | gifs → galaxyclusters]