Latest Posts by ad-astra-affecte-spe - Page 4

A beginner’s star-book, an easy guide to the stars and to the astronomical uses of the opera-glass, the field-glass and the telescope, 1912

The photos that NASAHubble & NASAWebb took of The Pillars of Creation inspired me deeply. I had to draw what I saw in the formation: A hand reaching into the universe. What an accomplishment for humankind and what a symbol for exploration and knowledge. Credit 2nd image: NASA

Uranus- JWST NIRCam

This image also shows 14 of the planet’s 27 moons: Oberon, Titania, Umbriel, Juliet, Perdita, Rosalind, Puck, Belinda, Desdemona, Cressida, Ariel, Miranda, Bianca, and Portia.

This picture shows Uranus's north polar cap as well as a storm just below the polar edge.

2023 December 16

Crescent Enceladus Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Peering from the shadows, the Saturn-facing hemisphere of tantalizing inner moon Enceladus poses in this Cassini spacecraft image. North is up in the dramatic scene captured during November 2016 as Cassini’s camera was pointed in a nearly sunward direction about 130,000 kilometers from the moon’s bright crescent. In fact, the distant world reflects over 90 percent of the sunlight it receives, giving its surface about the same reflectivity as fresh snow. A mere 500 kilometers in diameter, Enceladus is a surprisingly active moon. Data and images collected during Cassini’s flybys have revealed water vapor and ice grains spewing from south polar geysers and evidence of an ocean of liquid water hidden beneath the moon’s icy crust.

∞ Source: apod.nasa.gov/apod/ap231216.html

Orion, The Great Hunter

November 12, 1980: Voyager 1 made its closest approach to Saturn, flying within 124,000 kilometers (77,000 miles) of the ringed planet.

Cosmic Alphabet Soup: Classifying Stars

If you’ve spent much time stargazing, you may have noticed that while most stars look white, some are reddish or bluish. Their colors are more than just pretty – they tell us how hot the stars are. Studying their light in greater detail can tell us even more about what they’re like, including whether they have planets. Two women, Williamina Fleming and Annie Jump Cannon, created the system for classifying stars that we use today, and we’re building on their work to map out the universe.

By splitting starlight into spectra – detailed color patterns that often feature lots of dark lines – using a prism, astronomers can figure out a star’s temperature, how long it will burn, how massive it is, and even how big its habitable zone is. Our Sun’s spectrum looks like this:

Astronomers use spectra to categorize stars. Starting at the hottest and most massive, the star classes are O, B, A, F, G (like our Sun), K, M. Sounds like cosmic alphabet soup! But the letters aren’t just random – they largely stem from the work of two famous female astronomers.

Williamina Fleming, who worked as one of the famous “human computers” at the Harvard College Observatory starting in 1879, came up with a way to classify stars into 17 different types (categorized alphabetically A-Q) based on how strong the dark lines in their spectra were. She eventually classified more than 10,000 stars and discovered hundreds of cosmic objects!

That was back before they knew what caused the dark lines in spectra. Soon astronomers discovered that they’re linked to a star’s temperature. Using this newfound knowledge, Annie Jump Cannon – one of Fleming’s protégés – rearranged and simplified stellar classification to include just seven categories (O, B, A, F, G, K, M), ordered from highest to lowest temperature. She also classified more than 350,000 stars!

Type O stars are both the hottest and most massive in the new classification system. These giants can be a thousand times bigger than the Sun! Their lifespans are also around 1,000 times shorter than our Sun’s. They burn through their fuel so fast that they only live for around 10 million years. That’s part of the reason they only make up a tiny fraction of all the stars in the galaxy – they don’t stick around for very long.

As we move down the list from O to M, stars become progressively smaller, cooler, redder, and more common. Their habitable zones also shrink because the stars aren’t putting out as much energy. The plus side is that the tiniest stars can live for a really long time – around 100 billion years – because they burn through their fuel so slowly.

Astronomers can also learn about exoplanets – worlds that orbit other stars – by studying starlight. When a planet crosses in front of its host star, different kinds of molecules in the planet’s atmosphere absorb certain wavelengths of light.

By spreading the star’s light into a spectrum, astronomers can see which wavelengths have been absorbed to determine the exoplanet atmosphere’s chemical makeup. Our James Webb Space Telescope will use this method to try to find and study atmospheres around Earth-sized exoplanets – something that has never been done before.

Our upcoming Nancy Grace Roman Space Telescope will study the spectra from entire galaxies to build a 3D map of the cosmos. As light travels through our expanding universe, it stretches and its spectral lines shift toward longer, redder wavelengths. The longer light travels before reaching us, the redder it becomes. Roman will be able to see so far back that we could glimpse some of the first stars and galaxies that ever formed.

Learn more about how Roman will study the cosmos in our other posts:

Roman’s Family Portrait of Millions of Galaxies

New Rose-Colored Glasses for Roman

How Gravity Warps Light

Make sure to follow us on Tumblr for your regular dose of space!

Our Weird and Wonderful Galaxy of Black Holes

Black holes are hard to find. Like, really hard to find. They are objects with such strong gravity that light can’t escape them, so we have to rely on clues from their surroundings to find them.

When a star weighing more than 20 times the Sun runs out of fuel, it collapses into a black hole. Scientists estimate that there are tens of millions of these black holes dotted around the Milky Way, but so far we’ve only identified a few dozen. Most of those are found with a star, each circling around the other. Another name for this kind of pair is a binary system.That’s because under the right circumstances material from the star can interact with the black hole, revealing its presence. 

The visualization above shows several of these binary systems found in our Milky Way and its neighboring galaxy. with their relative sizes and orbits to scale. The video even shows each system tilted the way we see it here from our vantage point on Earth. Of course, as our scientists gather more data about these black holes, our understanding of them may change.   

If the star and black hole orbit close enough, the black hole can pull material off of its stellar companion! As the material swirls toward the black hole, it forms a flat ring called an accretion disk. The disk gets very hot and can flare, causing bright bursts of light.

V404 Cygni, depicted above, is a binary system where a star slightly smaller than the Sun orbits a black hole 10 times its mass in just 6.5 days. The black hole distorts the shape of the star and pulls material from its surface. In 2015, V404 Cygni came out of a 25-year slumber, erupting in X-rays that were initially detected by our Swift satellite. In fact, V404 Cygni erupts every couple of decades, perhaps driven by a build-up of material in the outer parts of the accretion disk that eventually rush in. 

In other cases, the black hole’s companion is a giant star with a strong stellar wind. This is like our Sun’s solar wind, but even more powerful. As material rushes out from the companion star, some of it is captured by the black hole’s gravity, forming an accretion disk.

A famous example of a black hole powered by the wind of its companion is Cygnus X-1. In fact, it was the first object to be widely accepted as a black hole! Recent observations estimate that the black hole’s mass could be as much as 20 times that of our Sun. And its stellar companion is no slouch, either. It weighs in at about 40 times the Sun.

We know our galaxy is peppered with black holes of many sizes with an array of stellar partners, but we've only found a small fraction of them so far. Scientists will keep studying the skies to add to our black hole menagerie.

Curious to learn more about black holes? Follow NASA Universe on Twitter and Facebook to keep up with the latest from our scientists and telescopes.

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

The four giant planets of our Solar System, as seen by NASA's James Webb Telescope.

Eruption of Tvashtar volcano on Jupiter's moon Io (March 1, 2007)

Going for a walk. Apollo 17 astronaut Ronald Evans leaves to the spacecraft to retrieve film cassettes from the Service Module, Dec 1972. Mr. Evans was Command Module Pilot & orbited the moon a record 75 times during the mission. He holds the record for most time spent in lunar orbit at just shy of 148 hours. He is the last human to orbit the moon solo. A historic figure in space pioneering.

SPACEMAS DAY 2 ✨🪐🌎☄️☀️🌕

There's a new space telescope in the sky: Euclid. Equipped with two large panoramic cameras, Euclid captures light from the visible all the way to the near-infrared. It took five hours of observing for Euclid's 1.2-meter diameter primary mirror to capture, the 1000+ galaxies in the Perseus cluster which lies 250 million light years away. More than 100,000 galaxies are visible in the background, some as far away as 10 billion light years. Euclid's initial surveys, covering a third of the sky and recording over 2 billion galaxies, will enable a study of how dark matter and dark energy have shaped our universe.

Image Credit: ESA, NASA

Galactic center of Milky Way © cosmic_background

Galaxies can merge, collide, or brush past one another — each of which has a significant impact on their shapes and structures. As common as these interactions are thought to be in the Universe, it is rare to capture an image of two galaxies interacting in such a visibly dynamic way. This image, from the NASA/ESA Hubble Space Telescope, feels incredibly three-dimensional for a piece of deep-space imagery.

The subject of this image is named Arp 282, an interacting galaxy pair that is composed of the Seyfert galaxy NGC 169 (bottom) and the galaxy IC 1559 (top).

Credits: ESA/Hubble & NASA, J. Dalcanton, Dark Energy Survey, J. Schmidt

Sagittarius dwarf irregular galaxy (sagDIG) © Hubble

The Rosetta Nebula and NGC 2244

At the heart of the Rosetta nebula is an open cluster of stars, which is NGC 2244. The entire structure sits at the end of a giant molecular cloud, and you can easily spot the tell tale columns and protostars at the head showing active star formation on-going.

The bottom image is from Chandra, which gives the purple/pink colours for X-Ray sources, used particularly in spotting black hole accretion disks, pulsars and supernova remnants, we can see it's a lively place !

The entire structure is in the constellation of Monoceros at around 5,200 light years from Earth.

Over 800 terrestrial exoplanets visualized and arranged according to their equilibrium temperature and size.

chart by u/mVargic

Lunar halo

@picabuzz

Andromeda over the Swiss Alps Image Credit: Dzmitry Kananovich

Sagittarius dwarf irregular galaxy (sagDIG) © Hubble

Galactic Center by NASA's Marshall Space Flight Center

Crab Nebula

Brothers Betelgeuse and Rigel

Sh2-136, Ghosts of the Cosmos

The California Nebula, NGC 1499 // Alex Weinstein

The bright star to the right is Menkib (ξ Persei), whose name comes from the Arabic phrase mankib al Thurayya meaning "shoulder of the Pleiades".

Francesco Levy, The Constellations of Summer

Lunar halo

@picabuzz