Saturn will be at its closest point to Earth on Sunday. Ever seen it with your own eyes? Over the next couple of days Saturn will the brightest thing near the Moon. You can see it wherever you are on Earth, just look towards the south east, about an hour after sunset! 🪐 So, Saturn is closest to the Moon tonight and Friday night (11-12 Aug), but Jupiter is closest from Saturday (13 Aug) onwards. To catch Jupiter, you'll have to wait a few hours after sunset. Scene should look something like this on Saturday evening. (All images via "Stellarium")

Actual footage of stars orbiting the supermassive black hole Sag A* at the center of our galaxy. One of the stars, S0-2, moves faster than 27 million kilometers per hour, or 2.6% the speed of light! Video source: and credit: Abhimat Gautam, Keck/UCLA Galactic Center Group

The observable universe is 93 billion light years wide and contains two trillion galaxies EACH containing countless billions of stars

The UNobservable universe beyond is at least 250 times wider, so its volume and galaxy content is 15 million times larger

Enjoy your Monday🥵 Because we understand the "shape" of the observable universe, we are able to extrapolate how big it should be in its entirety. "we" meaning cosmologists like @StartsWithABang who wrote about this in detail here. I recommend reading it over a drink! medium.com/starts-with-a-…

Stars are formed in dusty regions of space like the nebula below, so the process is normally difficult to see in visible light (eg. with Hubble). JWST uses infrared which allows us to actually see *through* cosmic dust, giving us (literally) a window into the birth of stars! You've really got to check out the full image taken by JWST btw, which can't be seen on Twitter anywhere near the full resolution. Check it out: webbtelescope.org/contents/media…. The highest resolution version has 15 times more pixels than a 4k image, you can even see background galaxies!

The video stems from my first/original 'science communication' animation idea. I had 500 followers when it dropped in Dec 2018 and was used to getting 0 or 1 likes on my posts before it. Because of your +ve reaction, I carried on 💪, so thank you!

https://twitter.com/physicsJ/status/1078865655540183040

I wanted to bring this up: I made an error in the 2018 vid. Someone corrected me on the length of day for Venus so I re-made the vid immediately. It's a teachable moment for what scientists do, so I left it, but all future posts are deleted when even the tiniest error is spotted

Did you know the planets don't technically orbit the Sun's center, instead, everything orbits our solar system center of mass, including the Sun! While our star holds 99.8% of the solar system's mass, Jupiter/Saturn hold most of the rest, so the Sun orbits them slightly (thread) Planet Earth follows the sun as it does this, keeping the Sun-Earth distance stable. Here's what our orbit looks like for the next hundred years. Note also that Earth's orbit is almost circular, so I put a circle on to show you how close it is

Make sure to catch these bright planets in the hours after sunset, wherever you are 🪐 Southern hemisphere folks will see it this way around. Images via Stellarium mobile app (a great purchase btw)

🚨 Our Jupiter discovery is now published!

We found that Jupiter's powerful polar auroras blast heat across the *entire planet* answering why for 50 years its upper atmosphere has measured hundreds of degrees hotter than sunlight alone can explain!

Paper nature.com/articles/s4158… Firstly, context! Jupiter is huge, let's just get that out of the way. Secondly, it rotates in just 10 hours. It's the largest AND fastest planet in our solar system.

Gravity on different Solar System bodies It might be surprising to see large planets have a pull comparable to smaller ones at the surface, for example Uranus pulls the ball down slower than at Earth! Why? The low average density of Uranus puts the surface far away from the majority of the mass.

Little-known fact: the Moon has a tail and every month we pass through it. Earth's gravity focuses the tail's atoms into a literal Moon-beam that can be seen at night during a New Moon with special cameras! Firstly, the Moon has an atmosphere, albeit a stupendously thin one. Secondly, some of this atmosphere is pushed by the Sun's radiation pressure & solar wind off the Moon, and that's what forms this huge tail

Let's leave the Solar System at the speed of light in real-time (thread)

The Sun seen from the emissions by Iron at >10 million Kelvin (yes, iron), which represents the material in flares!

June 12, 2021, 12:00:00 UTC
Distance: 0 AU
Light-time: 0 sec
Credit: NASA/SDO/Goddard We arrive at Mercury first, the closest planet to the Sun. Day/night temps are 430°C/ –180 °C!

June 12, 2021, 12:03:13 UTC
Distance: 0.39 AU
Light-time: 3min 13sec
Credit: MESSENGER spacecraft / K. Becker / NASA JPL / ASU / Johns Hopkins APL, Carnegie Institution of Washington

At 99% the speed of light you could get to Mars in 30 seconds from *your* perspective, when Mars is (about) closest to Earth

Observers on Earth however, would see you take 3 minutes 30 seconds

THAT is time dilation, it really happens, this is a fundamental aspect of reality. When something reaches light speed it doesn't experience time passing at all — it's the extreme end of time dilation. If you left Earth and could somehow accelerate to near light speed, you could navigate the cosmos in far less time, but everyone back home would be aging...

By the way, where do you think I'm from? Okay 1200 votes have been cast, probably enough of a sample! I'm from the UK (Shrewsbury, Shropshire, England, UK, Europe, Earth, Orion Arm, Milky Way, Local Group, Virgo cluster, Virgo super cluster, Universe). Half my family originate from Ireland & I lived in USA for 5 years

I once looked at this famous Superman ('78) scene in video editing software—

He appeared to go 20% faster than light for 10 seconds, but Earth was already rotating 1800x faster than normal from the start, implying the scene is a timelapse. If so, he only hit 200 km/s (0.07% c)

https://twitter.com/AriPirAriP/status/1356015508915515394

Other things:
It took Superman 7 seconds to reach light speed. Once he reached 120% of light speed it took 3 seconds for Earth to start rotating the other way, despite his constant velocity. He laps Earth exactly 6x per second, probably as fast as they could show it

Saturn's rings are a rainbow of ice scupted into position by gravity. Here's a natural colour 17 megapixel image taken by the Cassini spacecraft. Distances listed are from Saturn's center; the rings are ~5 Earths wide here! Credit: NASA/JPL/Space Sci Inst/CICLOPS Ring systems may be "temporary" lasting hundreds of millions or billions of years. It's unclear how old Saturn's rings are yet. We are fortunate to have them in our solar system right now, but I do wonder if we missed out on a Jupiter ring system. Full img photojournal.jpl.nasa.gov/catalog/PIA111…

The moment Jupiter and Saturn are closest in the sky on 21 Dec 2020

Los Angeles: 09:43
New York: 12:43
Rio de Janeiro: 14:43
London/UTC: 17:43
Paris/CET: 18:43
Istanbul: 20:43
Dubai: 21:43
New Delhi: 23:13
Tokyo: 02:43 (22 Dec)
Sydney: 04:43 (22 Dec)
(+/- minutes; see thread) +/- minutes because the size of the Earth, and its rotation, means different places will have a *very slightly* different line of sight at Jupiter and Saturn. E.g. London sees the gap close at 17:43, while Auckland, New Zealand sees it on 17:39 (UTC). London times were used above

TOMORROW Jupiter and Saturn will be at their closest separation in the sky since 1623 at 0.1° apart. Here's an animation showing exactly how close that is relative to a familiar object, the Moon! (Moon ONLY added to illustrate the scale) #GreatConjunction2020 You DO NOT want a configuration of the solar system in which the giant planets go infront of our Moon. Here's the video in 1080p:

On 21 December Jupiter and Saturn will be at their closest separation in the sky since 1623, at just 0.1° apart! In this new to-scale animation I follow the mid-point between them in the sky #GreatConjunction2020 Feel free to use this video wherever, no need to ask permission. On twitter it's 720p (and less, when it buffers). Here on youtube it's 1080p:

Here's what it looks like when one galaxy passes right through another. The galaxy on the right has an expanding ring of stars (like a shockwave), while the other has been stretched out! And do forgive the low resolution of the image, these are 500 million light years away. When the left galaxy passed through, the right galaxy would have been attracted to its own center due to the extra gravitational pull. After collisiding, the ring of material then expanded back out, likely because it still has orbital velocity and can escape its new, weak center

PSA: @ScienceWithJen is very likely a fake account. They used several accounts in just 2020, claiming to work at spaceX (until their account was reported & closed). Jobs claimed just in 2020: aerospace/engineering/flight ops, but all with an astrophysics masters degree.

https://twitter.com/drama_science/status/1311069263323631621

I suspected this in 2019 and since then numerous new examples of fakery keep coming in: people have DM'd to tell me about it from large space agencies. In the last week they moved over to a new account once again, and anyone asking Qs to them about it gets blocked

I have an science/art video idea but I don't have time to make, so I'll share it here if someone else is interested:

What if we had a video sequence that displayed 180 galaxies one after another, similar to below (cred: edd.ifa.hawaii.edu/inclination/in…), but in 1° inclination increments If a galaxy astronomer out there knows of a good table/database of galaxies which can be sorted by inclination, that would be a great first step: please let me know and I'll link it in this thread. I had a look around and didn't see much like that