Jansky - “A unit used in radio astronomy to indicate the flux density (the rate of flow of radio waves) of electromagnetic radiation received from outer space. A typical radio source has a spectral flux density of roughly 1 Jy. The jansky was named to honor Karl Gothe Jansky who developed radio astronomy in 1932.”
Jet - “A narrow stream of gas or particles ejected from an accretion disk surrounding a star or black hole.”
Julian date (JD) - “The interval of time in days (and fraction of a day) since Greenwich noon on Jan. 1, 4713 BC. The JD is always half a day off from Universal Time, because the current definition of JD was introduced when the astronomical day was defined to start at noon (prior to 1925) instead of midnight. Thus, 1995 Oct. 10.0 UT = JD 2450000.5.”
Julian year - “Exactly 365.25 days, in which a century (100 years) is exactly 36525 days and in which 1900.0 corresponds exactly to 1900 January 0.5 (from the Julian-date system, which is half a day different from civil time or UT). The standard epoch J2000.0, now used for new star-position catalogues and in solar-system-orbital calculations, means 2000 Jan. 1.5 Barycentric Dynamical Time (TDB) = Julian Date 2451545.0 TDB. When this dynamical, artificial “Julian year” is employed, a letter “J” prefixes the year.”
Kelvin - “A temperature scale used in sciences such as astronomy to measure extremely cold temperatures. The Kelvin temperature scale is just like the Celsius scale except that the freezing point of water, zero degrees Celsius, is equal to 273 degrees Kelvin. Absolute zero, the coldest known temperature, is reached at 0 degrees Kelvin or -273.16 degrees Celsius.”
Kepler’s First Law - “A planet orbits the Sun in an ellipse with the Sun at one focus.”
Kepler’s Second Law - “A ray directed from the Sun to a planet sweeps out equal areas in equal times.”
Kepler’s Third Law - “The square of the period of a planet’s orbit is proportional to the cube of that planet’s semi major axis; the constant of proportionality is the same for all planets.”
Kirkwood Gaps - “Regions in the main belt of asteroids where few or no asteroids are found. They were named after the scientist who first noticed them.”
Kuiper Belt - “A large ring of icy, primitive objects beyond the orbit of Neptune. Kuiper Belt objects are believed to be remnants of the original material that formed the Solar System. Some astronomers believe Pluto and Charon are Kuiper Belt objects.”
Is there any reason as to why the event horizon of a black hole is spherical?
There are rotating, and “non-rotating”/very slowly rotating black holes. Non-rotating* [or static] black holes’ event horizons have almost perfect spherical shapes determined by the Schwarzschild radius**. Rotating black holes’ event horizons have irregular, oblate-like, non-spherical shapes. [The slower the rotation of a black hole is, the more spherical, if not almost fully spherical, it’s event horizon will be. The faster the rotation of a black hole is, the less spherical, and more oblate it’s event horizon will be .] It’s continually argued that no black hole’s event horizon ever reaches a “perfect” spherical shape, but can come extremely close to seeming like it does, due to the lack of/slow rotation of the black hole itself and it’s dragging of spacetime.
*Non-rotating black holes are technically and physically impossible. If they appear non-rotating, it’s because the rate their rotation is so fractional it’s really hard to tell it’s actually moving at all. The mistake that all black holes’ event horizons are perfectly spherical is usually based off of the solution of the hypothetical Schwarzschild black hole, not a realistically physical object.
**”A Schwarzschild black hole is a perfectly spherical, static and non-rotating black hole. Basically, it is a point mass (with no height, width or depth) of infinite density or a singularity in the center with a gravitational field surrounding it. At the singularity, space and time as we know it stop.
A Schwarzschild black hole is the basic description of a still-standing black hole, however stars in nature rotate. You can’t apply Schwarzschild to real stars because when a spherical object spins it drags spacetime along with it." [x]
You can read more about rotating and non-rotating black holes here.
I hope this helps answer your question! Thanks for the ask!
Hey, I'm new to Tumblr's science community! I was wondering what I could do to make my blog stand out, as there are so many amazing blogs out there! Any advise for a newbie, like myself?
Hello dear! Welcome to the science community here on Tumblr! It’s always spectacular to have more informational blogs around here!
Well, there’s quite a few bits of *advice I can give you to make your page stand out amongst the numerous other science blogs. First things first, make sure your posts are tagged so that you can link certain topics in your sidebar/navigation. [ie. astronomy, health, cosmology, chemistry, biology, etc.] The easier your blog is to navigate, the more people will stay on it, and even continuously return due to your readers being able to find what they’re looking for right away.
My next bit of advice may not necessarily apply to you, depending on exactly what kind of science blog you’re aiming on running. You could cover all sciences, and that’s fine, many science pages on Tumblr do cover most subjects, and even some outside of science, but it’s best if whilst covering all subjects, you have a ‘theme’. Like my own page for example, I cover all sciences, but focus highly on Astronomy/Cosmology. So whilst providing information on all scientific fields, you can have a good percentage of your posts concerning mainly one and/or a couple specific scientific areas.
Also, fact check EVERYTHING you post and/or reblog. [And if necessary, you should post a warning if a touchy subject as TW - trigger warning - such as posts/topics concerning rape, abuse, etc.] As the Tumblr science/informational community is pretty reliable with sourcing and facts, most of tumblr consists of merely ‘picture/follow-back blogs’ and these people/pages are not reliable fact-wise. Due to this, besides people removing credit on a daily basis to take credit for work that isn’t theirs, they will pretty much take anything for your word, even if it’s not true at all because very few people seem to background check the information floating around before reblogging or even posting it. Snopes will become one of your best friends if you do this correctly, and don’t forget, stay skeptical. Also, wikipedia, whilst sometimes reliable, isn’t necessarily a completely solidly factual source on it’s own all the time, so try and stay away from using that as a main reference.
If you do happen to post something that isn’t necessarily the ‘full truth’ or even just plain wrong, don’t be embarrassed or upset if someone calls you out for it, as they most likely will. [And don’t be afraid to call other’s mistakes out respectfully if you see something being claimed as a fact when, in fact, it is wrong.] Constructive criticism is something most people get a daily dose of on Tumblr, if not negative criticism, as you’ll come to learn some people can be plain assholes. When dealing with respectful or disrespectful people, just be polite, and reply as respectfully and maturely as possible, unless of course they cross a line with their ridiculous disrespect, and thank them for pointing out your mistake. There’s no shame in being wrong as long as you learn from your mistakes and try your best to correct them. If you’re not making mistakes, then you’re not really learning.
SOURCE EVERYTHING [whilst making posts] containing content that is not originally yours to post. When you don’t source stuff, people will either put in their own url, or some off-source that people will assume is where the post’s original content came from, which can be misleading when you have people actually willing to click a “continue reading” or “via [put name of website here]” link because they’re actually trying to learn.
Another huge thing, don’t go overboard with your theme. A lot of people do this, sadly, and I’ve found it makes me not want to go back to their page as often because it’s just hard to focus on one thing, and everything’s a bit everywhere. I had that problem myself when I started, I had so much with not only my background [with bright coloured images of deep space], but the content in my sidebar/theme itself that it was a bit distracting from what I’m really trying to focus on, the information. The cleaner, the better, and the less gifs/widgets visible in your sidebar, the better. Also, infinite scroll is not always the best, though sometimes it’s wonderful. It’s, of course, depending on your theme and your own preferences.
NEVER be afraid to post science-related art/personal posts/what ever you are personally inspired by once in a while. That’s why it’s YOUR blog, whilst it may focus on science, you can still put up photos of yourself, personal opinions on certain subjects, and anything that inspires you. People really have a thing for getting to know the people behind the pages on tumblr, so don’t be scared to open up! For example, I’m a huge art-nerd, so I really love not just regular art, but sciencey art as well, especially sci-fi space art.And if you have an inner comic book geek just waiting to burst out, let it free! Tumblr has a huge, and ever growing community of amazing art, and artists, including thousands of great blogs dedicated to specifically comic books and/or graphic novels.
Last but not least, probably the most important, be interactive with your followers. What I mean is, be willing to answer questions for your followers, and especially anon*, and if you can’t at least give them a few educational/helpful links so they can head the right way with their own research. *I know this sounds silly but having anon on, especially with a science/informational/factual blog, is one of the best pieces of advice I can give you. People, more times than not, are intimidated/embarrassed when they don’t know something that they may personally feel they should know, or that everyone else knows, but they don’t. If you give your readers the option of being anon they’ll be much more willing to ask you some pretty good questions concerning science and the like. You shouldn’t really have an issue with anon-hate, maybe the oddly disrespectful or questionable asks here and there, but since you’re focusing mainly on science and factual things, there’s really no reason for anyone to send you harshly negative feedback.
As for your readers, whilst trying to maintain an interactive and open relationship with all of your followers, ask questions once in a while that people are able to reply to. Some of the questions I’ve used over time are things like, “Who’s your favourite scientist and why?” or “What area of science mosts interests you and why?”. As you can see, I try to steer away from “yes and no” questions, that way I get people’s personal opinions, and actually get to know people, and show them I’m willing to interact and listen to other’s POVs. The submit option is always a good thing to have on your page as well, the more of a community you make your page into, the more interesting topics and suggestions you will get from your readers about what they would like to see on your page/learn about. As a science page, people will be expecting you to be able to answer tons of different questions, and be well read up on your subjects, they expect a learning experience when following you/visiting your page, more times or not. So make sure you try to post relevant/up-to-date stories/subjects once in a while concerning the world of science.
You will come across probably the most eclectic group of people you’ve ever witnessed within the science community, but don’t let that scare you away. As long as you are open minded, willing to learn, know what you stand for, and against, as well as willing to accept constructive criticism, you should be good to go!
Tag your posts per subject/topic and link to them in your navigation and/or sidebar so people can easily navigate your page.
Make sure you background check and fact check everything you reblog, and especially everything you post. As a science blog, people will be relying on you to be 100% on top of the facts and knowing what you’re talking about. [Don’t rely on wikipedia as a resourceful and 100% solid fact-referencing site. Snopes, on the other hand, might just become your best friend.]
Be ready and willing to accept constructive criticism, and sometimes not-so-constructive criticism. Try to remain respectful, and don’t be ashamed to correct yourself. If you’re not making mistakes, then you’re not really learning/expanding/growing correctly.
Source everything!!!!! Outside of the informational community on tumblr, many people make up sources due to misinformation, a mistake, or some other odd reasoning, and more times than not never fact-check/background check anything. So before posting, and especially before reblogging a post, make sure the source provided matches up with the image and/or information.
Don’t put too much busy-nonsense on your blog to distract from your main focus, the scientific information. [Ie. don’t use too brightly coloured or flashy backgrounds, and don’t have a ridiculous amount of distracting ads/unnecessary gifs/images in your navigation/sidebar.]
Don’t be afraid to throw in some personal photos/posts and/or inspiration once in a while. Most people really love getting to know the person behind the blog.
Be interactive with your followers; be willing to take suggestions and/or submissions on topics to post about. Ask open questions so everyone can answer, having anon enabled for your ask box is usually encouraging in case people are timid about openly asking questions.
Keep an open mind, and don’t judge a book by it’s cover.
Have fun & science on!!
Also, I highly suggest following mostly all of the editors of the science tag on tumblr, and follow the science tagitself [you can track tags], as well as the blogs below:
Once you get yourself set up, you can also submit your page to Tumblr’s Science Directory, ScienceOn. [As well as looking through the pages already on there and following them.] And please, if you’re willing, you can message me the url of your science page and I will happily promote it to my followers when you’re comfortable sharing it with the public. The more science to spread the better, and the more followers you attain, the more of a reason to keep up with posting and keep bettering your page and it’s content. I wish you the best of luck, and honestly hope to hear from you off-anon. If I can help you out with anything at all, don’t be afraid to hit me up! Cheers [:
what do you mean about getting credits with coursura? i see it mentioning a certificate or something, but not actual college credit that you could potentially transfer over. jesus that would be a lifesaver for me personally, but it sounds a little too good to be true.
When I was browsing through the site, mind you this was maybe a month or two ago, a very small number of the courses I looked into had mentioned at the end of the ‘course’ or ‘semester’ options to take ‘final exams’ that could help you possibly acquire credits. Again, this was a while ago, before they added over 100+ more courses and most of the ‘brand name’ schools, so things most likely changed. And I agree, it sounds too good to be fully true.
Like I said in the reply-post, I have not personally signed up with Coursera, so I can’t vouch for it’s 100% legitimacy with everything. Please, everyone, research into anything [free-course related, or not] before signing up for an online service, they’ll snag you with the fine print. For some people Coursera is perfect, for others, they want a bit more of a hands-on approach to learning instead of just reading then discussing topics. And again, most “free” online courses do take your rights to any papers/projects you submit, so always be cautious. It’s all about personal preference.
When looking into “free” online courses, it’s good to look for the free text books, book syllabus and/or videos. I was recently suggested to look into Khan Academy which offers literally thousands of educational videos that are just as useful as a “online course”, and probably a bit easier to use in many aspects. They offer educational videos and exercises in pretty much any subject you could imagine, including test prep. But I feel you, anon, it’s most likely too good to be true in Coursera’s case since they have added all those new Universities and their courses. To get free or close to free credits like that is rarer than I’d like to admit, something I would definitely love to find in a substantial site/program.
Ice - “A term used to describe water or a number of gases such as methane or ammonia when in a solid state.”
Inclination - “A measure of the tilt of a planet’s orbital plane in relation to that of the Earth.”
Inferior Conjunction - “A conjunction of an inferior planet that occurs when the planet is lined up directly between the Earth and the Sun.”
Inferior Planet - “A planet that orbits between the Earth and the Sun. Mercury and Venus are the only two inferior planets in our solar system.”
Inflationary Scenario - “A modification of the Big Bang model in which a large cosmological constant exists temporarily early in the history of the Big Bang, leading to a rapid accelerating expansion of the Universe, which is then followed by the normal Big Bang model with a decelerating expansion.”
International Astronomical Union (IAU) - “An international organization that unites national astronomical societies from around the world and acts as the internationally recognized authority for assigning designations to celestial bodies and their surface features.”
Interstellar Medium - “The gas and dust that exists in open space between the stars.”
Ionosphere - “A region of charged particles in a planet’s upper atmosphere. In Earth’s atmosphere, the ionosphere begins at an altitude of about 25 miles and extends outward about 250.”
Iron Meteorite - “A meteorite that is composed mainly of iron mixed with smaller amounts of nickel.”
Irregular Galaxy - “A galaxy with no spiral structure and no symmetric shape. Irregular galaxies are usually filamentary or very clumpy in shape.”
Irregular Satellite - “A satellite that orbits a planet far away with an orbit that is eccentric and inclined. They also tend to have retrograde orbits. Irregular satellites are believed to have been captured by the planet’s gravity rather than being formed along with the planet.”
Isotropic - “The same in all directions. Anisotropic - not isotropic. Anisotropy - difference between different directions. In the standard color scheme for CMB anisotropy maps measured by the COBE DMR, red shows areas of the sky that are warmer, while blue shows the cooler regions.”
“The earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and in triumph they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of the dot on scarcely distinguishable inhabitants of some other corner of the dot. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity — in all this vastness — there is no hint that help will come from elsewhere to save us from ourselves. It is up to us. It’s been said that astronomy is a humbling, and I might add, a character-building experience. To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we’ve ever known.”—Carl Sagan
Are you familiar with John and Hank Green (also known as theVlogbrothers)? If not, you should check out SciShow and/or Crash Course on youtube. They aim to promote the pursuit of knowledge in a fantastically entertaining way. Just thought I'd throw it out there.
Oh my gosh of course! Both the Greens are AMAZING! I’m glad you brought this up, though. Definitely some of the more useful video-related sources I tend to forget much too easily. For those who aren’t familiar with John and Hank Green, aka the VlogBrothers, check out their shows SciShow and Crash Course.
Thanks for the suggestion, and if anyone else knows of some great educational sites, I’d love to know!
How was your trip to the late great Dr. Sagan's final resting place?
Ohhh haha nonono. I didn’t go!
I reblogged that quote from John aka theuniverseatlarge, and his url didn’t get put in there. He was the OP and is going to visit Dr. Sagan’s grave. I just fixed it to avoid further confusion! I wish I could go sooner than later, that would be very beautiful. Sorry for the confusion, anon!