Drops Of A Liquid Can Often Join A Pool Gradually Through A Process Known As The Coalescence Cascade

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Zeta Ophiuchus

A massive star plowing through the gas and dust floating in space. Zeta Oph is a bruiser, with 20 times the Sun’s mass. It’s an incredibly luminous star, blasting out light at a rate 80,000 times higher than the Sun! Even at its distance of 400 light years or so, it should be one of the brightest stars in the sky … yet it actually appears relatively dim to the eye.

Credit: NASA/Hubble

If it is just us, seems like an awful waste of space.

Carl Sagan (from Contact)

How Do Volcanoes Make Lightning?

“Volcanic lightning appears to occur most frequently around volcanoes with large ash plumes, particularly during active stages of the eruption, where flowing, molten lava creates the largest temperature gradients. The phenomena of lightning has been exquisitely recorded around a number of recent volcanic eruptions, including Iceland’s Eyjafjallajökull, Japan’s Sakurajima, Italy’s Mt. Etna, and Chile’s Puyehue, Calbuco and Chaiten volcanoes. But what you may not know is this phenomenon was not only captured during Mt. Vesuvius’ last eruption in 1944, but was accurately described nearly 2,000 years ago when it erupted all the way back in the year 79!”

Volcanoes are some of the most potentially destructive natural phenomena known to occur on our world. The most violent eruptions feature not only lava, but soot, ash, volatile gases, and even enormous chunks of rock hurled great distances. What you might not realize, however, is just how frequently these eruptions are accompanied by another spectacular show: volcanic lightning. Lightning isn’t only found in thunderstorms or other great electrical discharges between the clouds and the ground, but is produced in volcanic eruptions all throughout the world, and throughout history as well. After countless generations, where we wondered what could produce such an unusual but spectacular show, we’ve finally figured it out.

Come get the science behind how volcanoes make lightning, and enjoy some of the greatest photographs of this phenomena humanity’s ever taken!

Why Bennu?

Our OSIRIS-REx spacecraft will travel to a near-Earth asteroid, called Bennu, where it will collect a sample to bring back to Earth for study. 

But why was Bennu chosen as the target destination asteroid for OSIRIS-REx? The science team took into account three criteria: accessibility, size and composition.

Accessibility: We need an asteroid that we can easily travel to, retrieve a sample from and return to Earth, all within a few years time. The closest asteroids are called near-Earth objects and they travel within 1.3 Astronomical Units (AU) of the sun. For those of you who don’t think in astronomical units…one Astronomical Unit is approximately equal to the distance between the sun and the Earth: ~93 million miles.

For a mission like OSIRIS-REx, the most accessible asteroids are somewhere between 0.08 – 1.6 AU. But we also needed to make sure that those asteroids have a similar orbit to Earth. Bennu fit this criteria! Check!

Size: We need an asteroid the right size to perform two critical portions of the mission: operations close to the asteroid and the actual sample collection from the surface of the asteroid. Bennu is roughly spherical and has a rotation period of 4.3 hours, which is in our size criteria. Check!

Composition: Asteroids are categorized by their spectral properties. In the visible and infrared light minerals have unique signatures or colors, much like fingerprints. Scientists use these fingerprints to identify molecules, like organics. For primitive, carbon-rich asteroids like Bennu, materials are preserved from over 4.5 billion years ago! We’re talking about the start of the formation of our solar system here! These primitive materials could contain organic molecules that may be the precursors to life here on Earth, or elsewhere in our solar system.

Thanks to telescopic observations in the visible and the infrared, as well as in radar, Bennu is currently the best understood asteroid not yet visited by a spacecraft.

All of these things make Bennu a fascinating and accessible asteroid for the OSIRIS-REx mission.

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

Solar System: Things to Know This Week

Learn the latest on Cassini’s Grand Finale, Pluto, Hubble Space Telescope and the Red Planet.

1. Cassini’s Grand Finale

After more than 12 years at Saturn, our Cassini mission has entered the final year of its epic voyage to the giant planet and its family of moons. But the journey isn’t over. The upcoming months will be like a whole new mission, with lots of new science and a truly thrilling ride in the unexplored space near the rings. Later this year, the spacecraft will fly repeatedly just outside the rings, capturing the closest views ever. Then, it will actually orbit inside the gap between the rings and the planet’s cloud tops.

Get details on Cassini’s final mission

The von Kármán Lecture Series: 2016

2. Chandra X-Rays Pluto

As the New Horizon’s mission headed to Pluto, our Chandra X-Ray Observatory made the first detection of the planet in X-rays. Chandra’s observations offer new insight into the space environment surrounding the largest and best-known object in the solar system’s outermost regions.

See Pluto’s X-Ray

3. … And Then Pluto Painted the Town Red

When the cameras on our approaching New Horizons spacecraft first spotted the large reddish polar region on Pluto’s largest moon, Charon, mission scientists knew two things: they’d never seen anything like it before, and they couldn’t wait to get the story behind it. After analyzing the images and other data that New Horizons has sent back from its July 2015 flight through the Pluto system, scientists think they’ve solved the mystery. Charon’s polar coloring comes from Pluto itself—as methane gas that escapes from Pluto’s atmosphere and becomes trapped by the moon’s gravity and freezes to the cold, icy surface at Charon’s pole.

Get the details

4. Pretty as a Postcard

The famed red-rock deserts of the American Southwest and recent images of Mars bear a striking similarity. New color images returned by our Curiosity Mars rover reveal the layered geologic past of the Red Planet in stunning detail. 

More images

5. Things Fall Apart

Our Hubble Space Telescope recently observed a comet breaking apart. In a series of images taken over a three-day span in January 2016, Hubble captured images of 25 building-size blocks made of a mixture of ice and dust drifting away from the comet. The resulting debris is now scattered along a 3,000-mile-long trail, larger than the width of the continental U.S.

Learn more

Discover the full list of 10 things to know about our solar system this week HERE.

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

I believe in free education, one that’s available to everyone; no matter their race, gender, age, wealth, etc… This masterpost was created for every knowledge hungry individual out there. I hope it will serve you well. Enjoy!

FREE ONLINE COURSES (here are listed websites that provide huge variety of courses)

Alison 

Coursera

FutureLearn

open2study

Khan Academy

edX

P2P U

Academic Earth

iversity

Stanford Online

MIT Open Courseware

Open Yale Courses

BBC Learning

OpenLearn

Carnegie Mellon University OLI

University of Reddit

Saylor

IDEAS, INSPIRATION & NEWS (websites which deliver educational content meant to entertain you and stimulate your brain)

TED

FORA

Big Think 

99u

BBC Future

Seriously Amazing

How Stuff Works

Discovery News

National Geographic

Science News

Popular Science

IFLScience

YouTube Edu

NewScientist

DIY & HOW-TO’S (Don’t know how to do that? Want to learn how to do it yourself? Here are some great websites.)

wikiHow

Wonder How To

instructables

eHow

Howcast

MAKE

Do it yourself

FREE TEXTBOOKS & E-BOOKS

OpenStax CNX

Open Textbooks

Bookboon

Textbook Revolution

E-books Directory

FullBooks

Books Should Be Free

Classic Reader

Read Print

Project Gutenberg

AudioBooks For Free

LibriVox

Poem Hunter

Bartleby

MIT Classics

Many Books

Open Textbooks BCcampus

Open Textbook Library

WikiBooks

SCIENTIFIC ARTICLES & JOURNALS

Directory of Open Access Journals

Scitable

PLOS

Wiley Open Access

Springer Open

Oxford Open

Elsevier Open Access

ArXiv

Open Access Library

LEARN:

1. LANGUAGES

Duolingo

BBC Languages

Learn A Language

101languages

Memrise

Livemocha

Foreign Services Institute

My Languages

Surface Languages

Lingualia

OmniGlot

OpenCulture’s Language links

2. COMPUTER SCIENCE & PROGRAMMING

Codecademy

Programmr

GA Dash

CodeHS

w3schools

Code Avengers

Codelearn

The Code Player

Code School

Code.org

Programming Motherf*?$%#

Bento

Bucky’s room

WiBit

Learn Code the Hard Way

Mozilla Developer Network

Microsoft Virtual Academy

3. YOGA & MEDITATION

Learning Yoga

Learn Meditation

Yome

Free Meditation

Online Meditation

Do Yoga With Me

Yoga Learning Center

4. PHOTOGRAPHY & FILMMAKING

Exposure Guide

The Bastards Book of Photography

Cambridge in Color

Best Photo Lessons

Photography Course

Production Now

nyvs

Learn About Film

Film School Online

5. DRAWING & PAINTING

Enliighten

Ctrl+Paint

ArtGraphica

Google Cultural Institute

Drawspace

DragoArt

WetCanvas

6. INSTRUMENTS & MUSIC THEORY

Music Theory

Teoria

Music Theory Videos

Furmanczyk Academy of Music

Dave Conservatoire

Petrucci Music Library

Justin Guitar

Guitar Lessons

Piano Lessons

Zebra Keys

Play Bass Now

7. OTHER UNCATEGORIZED SKILLS

Investopedia

The Chess Website

Chesscademy

Chess.com

Spreeder

ReadSpeeder

First Aid for Free

First Aid Web

NHS Choices

Wolfram Demonstrations Project

Please feel free to add more learning focused websites. 

*There are a lot more learning websites out there, but I picked the ones that are, as far as I’m aware, completely free and in my opinion the best/ most useful.

The latest from Brock Davis - love his work! 

NASA logo. April 27, 2015 As the saying goes, timing is everything. More so in 21st-century space exploration where navigating spacecraft precisely to far-flung destinations—say to Mars or even more distant Europa, a moon of Jupiter—is critical. NASA is making great strides...

All the times science fiction became fact

I don’t usually go for these really-big-ads-disguised-as-infographics (Really? Sci-fi ink & toner?), but this one was too cool to pass up.

Unfortunately, no hoverboards yet. But we’ve still got 15 months before time runs out on that one:

Bonus: Why are some science fiction authors so good at predicting the future? Check out this episode of It’s Okay To Be Smart where I talk all about that:

(via io9)