Pandora-allan - PAN-DORA

@knowitowl I'm sorry I didn't saw this for a while but THANKS FOR THE TAG!!

Last song: Hold on by Chord Overstreet

Last movie: Red shoes and the Seven Dwarfs (bc Merlin is CUTE)

Currently watching: Online lectures:/

Currently reading: The English Patient by Michael Ondaatje

Currently craving: pasta with shrimp:)

Tagging at anyone who wants to do this:)))

Tag people you’d like to get to know better

I was tagged by @psycho-crazy-pineapples

Last Song: I Don’t Want to be Friends by Jake Scott

Last Movie: Scooby-Doo 2: Monsters Unleashed

Currently Watching: Rewatching/Bingewatching Over the Garden Wall today as my annual pre-halloween tradition

Currently Reading: Small Spaces by Katherine Arden and Stocking and Spells by Nancy Warren

Currently Craving: apple pie

tagging: @viktorkrumn @comatose–overdose @skytlake @namida221b @moonlandingwasfaked @serooks and anyone who feels like it!

Weird and Wonderful Irregular Galaxies

Spiral and elliptical galaxies seem neatly put together, but what happened to irregular galaxies? Irregular galaxies have one-of-a-kind shapes and many look like blobs! Why do they look the way they do? Astronomers think the uniqueness of these galaxies results from their interactions with other galaxies — like when they pass close to one another or even collide!

Looking back at the early universe with the help of our Hubble Space Telescope’s “deep field” observations, astronomers can peek at galaxies millions and billions of light-years away. They noticed that these far-away galaxies appear unusually messy, showing more star formation and mergers than galaxies closer to the Milky Way.

We also see irregular galaxies closer to home, though. Some may form when two galaxies pass close together in a near-miss. When this happens, their gravity pulls stars out of place in both galaxies, messing up the neat structure they originally had as spiral or elliptical galaxies. Think of it like this: you happen to have a pile of papers sitting at the edge of a table and when someone passes close by the papers become ruffled and may scatter everywhere! Even though the two galaxies never touched, gravity's effects leave them looking smeared or distorted.

Some irregular galaxies result from the collision between two galaxies. And while some of these look like a blob of stars and dust, others form dazzling ring galaxies! Scientists think these may be a product of collisions between small and large galaxies. These collisions cause ripples that disturb both galaxies, throwing dust, gas, and stars outward. When this happens, it pushes out a ring of material, causing gas clouds to collide and spark the birth of new stars. After just a few million years, stars larger than our Sun explode as supernovae, leaving neutron stars and black holes throughout the ring!

Not all galaxy collisions create irregular galaxies — our Milky Way spiral galaxy has gone through many mergers but has stayed intact! And for some interacting galaxies, being an irregular galaxy may just be a phase in their transformation. We’re observing them at a snapshot in time where things are messy, but they may eventually become neat and structured spirals and ellipticals.

Irregular galaxies are similar to each other, but unique and beautiful because of their different interactions, whether they’re just passing another galaxy or taking part in a dramatic collision. Keep up with NASA Universe on Facebook and Twitter where we post regularly about galaxies.

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

"I never knew I could feel so much pain, and yet be so in love with the person causing it..."

Jeyna is canon in my heart and that’s all that matters

Everyone says love hurts, but that is not true. Loneliness hurts. Rejection hurts. Losing someone hurts. Envy hurts. Everyone gets these things confused with love, but in reality love is the only thing in this world that covers up all pain and makes someone feel wonderful again. Love is the only thing in this world that does not hurt.

— Meša Selimović

Lmao I would do the same

Here’s how it works: we board the train. I sit at the back of the train, facing forward. You sit at the front of the train, glancing back. There is a distance, d, between us. The doors slide shut. The train lurches into motion.

If the train was moving at a perfectly constant velocity, we could pull the shades down over the windows, close our eyes, block out all other frames of reference, and believe that we were standing still, that our journey had not yet started, that it was not yet too late to stand up and disembark and still be standing at the station. But for now there is only acceleration, unmistakable, the train building, building speed, hurtling off towards the future.

It goes like this: we pass light and shade and light and shade and light.

Each time, a shaft of light enters from the very front of the train, through the engineer’s window, passes you and and travels the length of d all the way to the back of the train at 299,792,458 meters per second to reach my eyes. Then a moment’s shadow, then the next shaft of light, and so on, at regular intervals, so that in this way we can keep time.

We are constantly accelerating.

In the infinitesimal amount of time it takes for a shaft of light to travel the length of d, I have been accelerated forward ever so infinitesimally to meet it, reducing the distance each successive beam of light has to travel, narrowing the intervals between them from what you experience up in front, quickening the beats of light and shade and light and shade and light.

Time dilates.

Let’s pretend: that before we boarded we set our watches to move in sync, that they beat in perfect unison, that by some coincidence each tick marks the precise interval between shafts of light from my perspective. Let’s pretend that I am sitting here in the back, my world in order, moving with perfect regularity. The speed of light is a constant. Tick, tick, tick, for every burst of light.

Even then, in the front, though your conscious mind could not possibly begin to perceive it, you might subconsciously begin to sense the irregularity: that your watch was moving faster, out of sync, that each tick came a fraction of a nanosecond before the next beam of light; that, on a long enough time frame, you would eventually come to overtake it, that you would gain an extra second, then another, then another, time compounding inevitably until we both knew for sure that I was lagging behind.

We have to accept this: that the speed of light is a constant, no matter where we are relative to each other, no matter our velocities, no matter the directions that we’re headed. That in the equation of S = d / t, speed is distance divided by time, it is time that has to change to compensate. That if we are to exist under the same laws of physics, we have to accept the seconds, minutes, hours, days, years, all the relative differences between us.

I am seated on the back of the train, looking forward into the future. You are seated on the front of the train, looking back into the past.

Porthcaw - England (by Tony Armstrong-Sly) 

The Lives, Times, and Deaths of Stars

Who among us doesn’t covertly read tabloid headlines when we pass them by? But if you’re really looking for a dramatic story, you might want to redirect your attention from Hollywood’s stars to the real thing. From birth to death, these burning spheres of gas experience some of the most extreme conditions our cosmos has to offer.

All stars are born in clouds of dust and gas like the Pillars of Creation in the Eagle Nebula pictured below. In these stellar nurseries, clumps of gas form, pulling in more and more mass as time passes. As they grow, these clumps start to spin and heat up. Once they get heavy and hot enough (like, 27 million degrees Fahrenheit or 15 million degrees Celsius), nuclear fusion starts in their cores. This process occurs when protons, the nuclei of hydrogen atoms, squish together to form helium nuclei. This releases a lot of energy, which heats the star and pushes against the force of its gravity. A star is born.

Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

From then on, stars’ life cycles depend on how much mass they have. Scientists typically divide them into two broad categories: low-mass and high-mass stars. (Technically, there’s an intermediate-mass category, but we’ll stick with these two to keep it straightforward!)

Low-mass stars

A low-mass star has a mass eight times the Sun’s or less and can burn steadily for billions of years. As it reaches the end of its life, its core runs out of hydrogen to convert into helium. Because the energy produced by fusion is the only force fighting gravity’s tendency to pull matter together, the core starts to collapse. But squeezing the core also increases its temperature and pressure, so much so that its helium starts to fuse into carbon, which also releases energy. The core rebounds a little, but the star’s atmosphere expands a lot, eventually turning into a red giant star and destroying any nearby planets. (Don’t worry, though, this is several billion years away for our Sun!)

Red giants become unstable and begin pulsating, periodically inflating and ejecting some of their atmospheres. Eventually, all of the star’s outer layers blow away, creating an expanding cloud of dust and gas misleadingly called a planetary nebula. (There are no planets involved.)

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

All that’s left of the star is its core, now called a white dwarf, a roughly Earth-sized stellar cinder that gradually cools over billions of years. If you could scoop up a teaspoon of its material, it would weigh more than a pickup truck. (Scientists recently found a potential planet closely orbiting a white dwarf. It somehow managed to survive the star’s chaotic, destructive history!)

High-mass stars

A high-mass star has a mass eight times the Sun’s or more and may only live for millions of years. (Rigel, a blue supergiant in the constellation Orion, pictured below, is 18 times the Sun’s mass.)

Credit: Rogelio Bernal Andreo

A high-mass star starts out doing the same things as a low-mass star, but it doesn’t stop at fusing helium into carbon. When the core runs out of helium, it shrinks, heats up, and starts converting its carbon into neon, which releases energy. Later, the core fuses the neon it produced into oxygen. Then, as the neon runs out, the core converts oxygen into silicon. Finally, this silicon fuses into iron. These processes produce energy that keeps the core from collapsing, but each new fuel buys it less and less time. By the point silicon fuses into iron, the star runs out of fuel in a matter of days. The next step would be fusing iron into some heavier element, but doing requires energy instead of releasing it.  

The star’s iron core collapses until forces between the nuclei push the brakes, and then it rebounds back to its original size. This change creates a shock wave that travels through the star’s outer layers. The result is a huge explosion called a supernova.

What’s left behind depends on the star’s initial mass. Remember, a high-mass star is anything with a mass more than eight times the Sun’s — which is a huge range! A star on the lower end of this spectrum leaves behind a city-size, superdense neutron star. (Some of these weird objects can spin faster than blender blades and have powerful magnetic fields. A teaspoon of their material would weigh as much as a mountain.)

At even higher masses, the star’s core turns into a black hole, one of the most bizarre cosmic objects out there. Black holes have such strong gravity that light can’t escape them. If you tried to get a teaspoon of material to weigh, you wouldn’t get it back once it crossed the event horizon — unless it could travel faster than the speed of light, and we don’t know of anything that can! (We’re a long way from visiting a black hole, but if you ever find yourself near one, there are some important safety considerations you should keep in mind.)

The explosion also leaves behind a cloud of debris called a supernova remnant. These and planetary nebulae from low-mass stars are the sources of many of the elements we find on Earth. Their dust and gas will one day become a part of other stars, starting the whole process over again.

That’s a very brief summary of the lives, times, and deaths of stars. (Remember, there’s that whole intermediate-mass category we glossed over!) To keep up with the most recent stellar news, follow NASA Universe on Twitter and Facebook.

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