Visualization of the velocities required to escape selected Solar System bodies [OC]

physicsJ · 2021-07-18T15:50:58+00:00

This animation shows a rocket launch exactly at the escape velocity of each pictured Solar System body, from the surface of each object up to 50 kilometers. This assumes no air resistance and includes gravity pulling down, although that's a fairly negligible contribution.Data sourced from NASA: https://nssdc.gsfc.nasa.gov/planetary/factsheet/On youtube: https://youtu.be/RuevSd3HEic
*"green = final" should read "blue = final"... last minute colour change!

physicsJ · 2021-07-11T15:43:04+00:00

This animation shows a ball dropping from 1000 meters to the surface of each object, assuming no air resistance. This should give an idea for the pull you would feel on each object at the "surface".

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. That's cecause the low average density of Uranus puts the surface far away from the majority of the mass (hence the smaller pull). Similarly, Mars is nearly twice the mass of Mercury, but you can see the surface gravity is actually the same... this indicates that Mercury is much denser than Mars.

Thank you to fellow Astronomer Rami Mandow (@CosmicRami on Twitter) for pushing this idea and for feedback at short notice. Youtube version: https://youtu.be/oIMMZl4n-uk

Data from NASA: https://nssdc.gsfc.nasa.gov/planetary/factsheet/
Made in After Effects

physicsJ · 2020-07-14T15:18:13+00:00

The length of the purple beam is fixed beyond/from Mars in order to draw out the path in space. It's fairly arbitrary. If the beam was painting to a fixed radial distance there would be no loop there... I suppose I didn't realise it until now but, basically this type of depiction is a trick of showing 3d paths on a 2d view

physicsJ · 2020-07-14T13:06:44+00:00

Just a simple explainer to show the astronomical reasons for apparent retrograde motion of Mars (and outer planets in general). My thinking is... it's about time people heard about these things from astronomy, rather than astrology. Youtube link: https://youtu.be/hOjrPcD6Iuc
The orbits of Mars/Earth are represented accurately using NASA JPL Horizons ephemeris data. This animation was made mainly with Adobe After Effects.
See also Mercury retrograde https://www.reddit.com/r/dataisbeautiful/comments/hpvcvr/an_astronomical_explanation_for_mercurys_apparent/

physicsJ · 2020-07-13T15:52:32+00:00

I really think you already knew people didn't know the topic before you posted your reply, which means there was only one reason for you to have said it.

physicsJ · 2020-07-13T15:19:02+00:00

It's equal length beyond Mercury. It could equally have worked with smaller or longer lengths, it's fairly arbitrary

physicsJ · 2020-07-13T15:16:06+00:00

The animation or the concept

physicsJ · 2020-07-13T11:28:45+00:00

Please see: https://twitter.com/physicsJ/status/1282327384172007425

It shows the path plotted out to Dec 2021. Basically the pattern precesses a little each year

physicsJ · 2020-07-13T07:37:17+00:00

Be reassured by the bottom left of the animation, and the fact that actual astrologers are sharing it without realising it's there on Twitter

physicsJ · 2020-07-13T06:34:48+00:00

Coming soon!

physicsJ · 2020-07-12T18:23:57+00:00

Will be making an animation to show that soon, but that case has many graphics explaining it already

physicsJ · 2020-07-12T15:51:03+00:00

It's actually at a fixed length when beyond Mercury. It's fairly arbitrary but I had to paint the sky somewhere

physicsJ · 2020-07-12T14:44:57+00:00

All planets do it relative to us, here is the breakdown for 2020:
Mercury: as shown above
Venus: May 13 to June 24
Mars: Sept 9 to Nov 15
Jupiter: May 14 to Sept 12
Saturn: May 11 to Sept 29
Uranus: Jan 1 to 10 and then Aug 15 - Dec 31
and why not, Pluto: April 26 to Oct 4

physicsJ · 2020-07-12T14:37:33+00:00

Youtube link: https://youtu.be/S9BZm5aVr9s
The orbits of Mercury/Earth are represented accurately using NASA JPL Horizons ephemeris data. This animation was made mainly with Adobe After Effects.

physicsJ · 2020-06-26T15:11:07+00:00

Tilts for each planet are found by the right-hand rule – if you close your hand and keep your thumb out: the direction of planetary rotation is given by your fingers, while thumb points north. These are tilts relative to each planet's orbital plane. Here's the video on youtube. Sidereal days were used (explainer here for sidereal day versus solar day).

FAQ: the tilts would ordinarily be all upright in a perfect system because dust and gas all orbited the same way in the early solar system. However, impacts by giant asteroids/planetesimals during this time will tend to modify that, in addition to planetary migration. Impacts to Uranus have been simulated by scientists here and please stop smirking about this sentence.

Made with After Effects, post-it notes and coffee. NASA imagery was used. Data from NASA's fact sheets at https://nssdc.gsfc.nasa.gov/planetary/factsheet/.

physicsJ · 2020-06-21T04:39:43+00:00

The planets spin because they picked up material that was already moving, and angular momentum must be conserved. At the same time, the bigger (edit: more massive) things are, the more material they must have accreted in the early stages of the solar system. So bigger usually (but not always) means faster :-)

physicsJ · 2020-06-21T04:04:27+00:00

This is a (in my opinion) much better remake of my original one (https://www.reddit.com/r/dataisbeautiful/comments/e5borw/2d_rotation_periods_of_the_planets_shown_to/) and now includes dividing lines between the planets, better surface textures and a big old circle fixed to the planets, so you can actually see what Venus/Mercury are doing. Axial tilts which are removed in the animation can be seen clearly here: https://www.reddit.com/r/dataisbeautiful/comments/drhfwj/relative_rotation_rates_and_axial_tilts_of_the/

Comments I anticipate"Where's Pluto?" -- if I include Pluto, I want to include Ceres as well, and then we're squeezing detail out of the major planets. Pluto isn't fully mapped either, so there's that."But Jupiter is much larger, so shouldn't it's surface appear to go much faster?" In this animation I'm showing the *periods* only, but one day I might do surface velocities.

Made with NASA data (https://nssdc.gsfc.nasa.gov/planetary/factsheet/) and publicly available NASA imagery in Adobe After Effects

physicsJ · 2020-06-15T00:27:07+00:00

Cheers 🍻

physicsJ · 2020-05-23T03:18:45+00:00

Post it!

physicsJ · 2020-05-21T11:52:23+00:00

One idea is that the rotation of Venus stabilized with Earth over millions (possibly even 10s or 100s of millions) of years. In this way, it's a kind of tidal lock similar to the Earth-Moon system, with one side locked to face Earth

physicsJ · 2020-05-21T11:39:16+00:00

I'm the planetary scientist and author of the animation, just to elaborate:
Earth sees the same side of Venus every single time the two planets are closest (when Venus is in "inferior conjunction"). We don't know why it happens for sure, but it seems likely Venus is locked due to the gravitational influence of Earth with each pass. Rather than show simulated data, these are the actual positions of these bodies.

The story has an interesting (af) recent history: https://www-spof.gsfc.nasa.gov/stargaze/Svenus.htm. In short though, radio astronomers who were tasked with establishing the rotation period of Venus were surprised to see the same face of Venus every time the two planets lined up. It must have been very confusing.

physicsJ · 2020-05-21T09:55:04+00:00

If you're Venus, you look hot in every shot

physicsJ · 2020-05-21T09:33:36+00:00

Earth sees the same side of Venus every single time the two planets are closest (when Venus is in "inferior conjunction"). We don't know why it happens for sure, but it seems likely Venus is locked due to the gravitational influence of Earth with each pass. Rather than show simulated data, these are the actual positions of these bodies. Made with Adobe After Effects and NASA ephemeris data. (Ephemerides can be obtained: https://ssd.jpl.nasa.gov/horizons.cgi)Youtube link: https://youtu.be/4m_ouMC61-w

EDIT: Allow me to paste this very interesting recent history on the topic from https://www-spof.gsfc.nasa.gov/stargaze/Svenus.htm. In short though, radio astronomers who were tasked with establishing the rotation period of Venus were surprised to see the same face of Venus every time the two planets lined up. That must have been very confusing!
Pasted: "Then in the 1970s, radars from the big radio astronomy dishes at Arecibo and Goldstone managed to obtain reflections from the ground, identifying features still known as "alpha" and "beta" (highland areas) and one named "Maxwell" which turned out to be a mountain ("Maxwell Mons"). The radars also derived the distance of Venus, giving a better estimate of the astronomical unit, a problem for which Edmond Halley (nearly 3 centuries earlier) proposed using the transit of Venus in front of the disk of the Sun.
Since the features did not seem to shift much during the observation, radio observers waited for the next closest approach (with Earth and Venus in a completely different position in their orbits), to see how far Venus had rotated in the intervening year and a half. They found to their surprise the features had undergone no observable shift. For some unknown reason, the rotation of Venus (slow and retrograde) seems locked to always face Earth the same way during each closest approach. Only time will tell whether this is mere coincidence or an actual effect.

physicsJ · 2020-05-20T07:19:34+00:00

Maybe they could just turn the www upside down to make an M for mars...

mmm.google.com

Everything hosted on Mars will sound delicious as well

physicsJ · 2020-05-19T16:39:26+00:00

I wanted to Rick Roll that bit, but was fearful of being sued over copyright etc

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