Freelance serendipidist and reborn feminist. Interested in politics, environment and people. I blog and reblog things I find curious, interesting and inspiring.
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:
“Titanic’s Captain Smith seen drilling holes into the hull, more at 11.”
That’s the worst possible fucking idea
I agree with all the above, but here’s why they’re doing it:
“The company’s customer base fell by 200,000 subscribers during the January-March period, according to its quarterly earnings report released Wednesday. It’s the first time that Netflix’s subscribers have fallen since the streaming service became available throughout most of the world outside of China six years ago.
The drop this year stemmed in part from Netflix’s decision to withdraw from Russia to protest the war against Ukraine, resulting in a loss of 700,000 subscribers.
Netflix acknowledged its problems are deep rooted by projecting a loss of another 2 million subscribers during the April-June period.
Netflix is hoping to reverse the tide by taking steps it has previously resisted, including blocking the sharing of accounts and introducing a lower-priced — and ad-supported — version of its service.”
Spectacularly camouflaged to mirror kelp or seaweed, the leafy sea dragon (Phycodurus eques) inhabits seagrass meadows and seagrass beds around the southern coast of Australia.
Like seahorse males, sea dragon dads are the ones to carry the developing offspring, up to 100-250 fertilized eggs. But while seahorses have a pouch, sea dragons tuck their precious cargo under their tails into “eggcups” that hold one egg each, nourishing it with oxygen until hatching day.
The crows she feeds obviously have their own little lives. They go about their business, and they spot *pretty thing* or /unique thing/ in question. What gets me is that the *first* thing on their minds as recipient of this thing is the little girl that feeds them.
They spot a thing, and immediately must think, “that nice girl with delicious foodstuffs must have this to show my gratitude.”
Crows and ravens are so cool. I have lots of them near my home. When my dog is bored they dive bomb her with twigs they pick up so she can chase them. They seem to enjoy entertaining her.
