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physicsJ's profile
Dr. James O'Donoghue
Dr. James O'Donoghue
Dr. James O'Donoghue
@physicsJ

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Dr. James O'Donoghue

@physicsJ

Planetary Scientist @NASAGoddard. Researching: #Saturn #Rings #Aurora #Jupiter #GreatRedSpot #Atmospheres From UK, in US, Japan 2019. Tweets/animations my own.

Maryland, USA
jamesodonoghue.wixsite.com/home
Joined December 2010

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    Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018

    *NEW* Final version: FASTER, longer, and corrected thanks to Twitter! 👍 Day length (sidereal) & axial tilt for the 8 largest planets in our solar system! Which planet best represents you? 🧐 HD Download for educators etc: https://tinyurl.com/y85u2ev7  #SolarSystem #SciCommpic.twitter.com/RPD8aRpUzr

    9:07 am - 29 Dec 2018
    • 4,305 Retweets
    • 8,146 Likes
    • Vadim Kaburgan つじ♡ようこ Shio Khushboo Yadav Franca D. 🇩🇪 Joan Soler i Gironès 黒田 基 (Motoru KURODA) Silvi. Ryan Curran
    208 replies . 4,305 retweets 8,146 likes
      1. New conversation
      2. Joachim L. Dagg‏ @jo_dagg 29 Dec 2018
        Replying to @physicsJ

        Is 1d = 24h or 1d = 23h+56m then?

        1 reply . 1 retweet 2 likes
      3. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @jo_dagg

        A Solar day, 24hr, is the time between two sunsets. A Sidereal day, 23h 56m, is the time Earth spins around 360 deg relative to the relatively fixed stars surrounding us.

        1 reply . 4 retweets 26 likes
      4. Joachim L. Dagg‏ @jo_dagg 29 Dec 2018
        Replying to @physicsJ

        Yeah, but what is MArs's rotation time in hours? 24h 32m I guess.

        1 reply . 1 retweet 0 likes
      5. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @jo_dagg

        Nah, all the times on that are sidereal, meaning they literally need to revolve 360 degrees. The problem with a Solar day is that when the planets move around the sun, the sun is slightly in a different place. This is exaggerated but shows it:pic.twitter.com/Mpry0TTZqg

        2 replies . 4 retweets 24 likes
      6. Joachim L. Dagg‏ @jo_dagg 29 Dec 2018
        Replying to @physicsJ

        If 1d = 23h+56m (sideral earth day), then you should have answered "yes," because 1d+36m = 24h+32m. Otherwise, I just don't understand.

        1 reply . 0 retweets 2 likes
      7. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @jo_dagg

        Ohh, this is very subtle, I see what you mean now. I was using our own definition of day when I say "d" anywhere. So for Mars, it's 24h + 36m. The alternative for this would have been for me to quote everything as hours, but it wouldn't be helpful to show Mercury/Venus in hours

        2 replies . 0 retweets 7 likes
      8. David Clapham‏ @DClaphamFRAS 30 Dec 2018
        Replying to @physicsJ @jo_dagg

        Opinion. Consistent units should be chosen to allow meaningful comparisons: it would be more helpful to show everything in hours and minutes than to introduce possible misunderstandings such as this.

        1 reply . 0 retweets 0 likes
      9. Dr. James O'Donoghue‏ @physicsJ 30 Dec 2018
        Replying to @DClaphamFRAS @jo_dagg

        All units are converted to those which regular people deal with. Mercury and Venus would mean people gettint out calculators. Having these periods be *instantly graspable* was important to this. Saying that though...I was 50/50 on saying hr+min for Mars!

        1 reply . 1 retweet 7 likes
      10. 4 more replies
      1. New conversation
      2. Emily Lakdawalla‏ @elakdawalla 29 Dec 2018
        Replying to @physicsJ

        Would it be okay with you if I posted a downsampled animated gif version in our image library, credited to you of course, with a link to the mp4 version hosted on our Amazon S3 site?

        1 reply . 1 retweet 24 likes
      3. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @elakdawalla

        Hi Emily, absolutely! Let me know if you need different aspect ratios etc. 👍

        1 reply . 0 retweets 3 likes
      4. Kevin Pluck‏ @kevpluck 29 Dec 2018
        Replying to @physicsJ @elakdawalla

        Here's my gif attempt, got it to loop after to earth rotations.pic.twitter.com/TlCcSmDX7E

        3 replies . 11 retweets 54 likes
      5. Kevin Pluck‏ @kevpluck 29 Dec 2018
        Replying to @kevpluck @physicsJ @elakdawalla

        *two earth rotations

        1 reply . 0 retweets 3 likes
      6. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @kevpluck @elakdawalla

        Ah nice. This is really crisp!

        1 reply . 0 retweets 4 likes
      7. Kevin Pluck‏ @kevpluck 29 Dec 2018
        Replying to @physicsJ @elakdawalla

        Cheers! not bad for 256 colours! I scaled it to 960x536 and weighs in at 13mb.https://www.dropbox.com/s/db93jjttucq0xid/8planets_ODonoghue_Educators_960x536.gif?dl=0 …

        1 reply . 2 retweets 10 likes
      8. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @kevpluck @elakdawalla

        Sweet, thanks! Nabbing that! 👍

        1 reply . 0 retweets 2 likes
      9. Kevin Pluck‏ @kevpluck 29 Dec 2018
        Replying to @physicsJ @elakdawalla

        You're very welcome! And thank you, excellent holiday project!

        0 replies . 0 retweets 4 likes
      10. End of conversation
      1. New conversation
      2. Scott Sutherland ( 🌦️ 🌩️ 🌀 🌙 🚀 🛰️)‏Verified account @ScottWx_TWN 29 Dec 2018
        Replying to @physicsJ

        Very cool! Just as a bug report, at around 0:27-0:28, there's a few glitches in the video. It pixelates badly and the colours go wonky.pic.twitter.com/JKraL4XzXF

        1 reply . 0 retweets 3 likes
      3. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @ScottWx_TWN

        I actually don't see this in the pre-uploaded (checked each frame) and uploaded versions, on my laptop or phone, hmm

        1 reply . 0 retweets 0 likes
      4. Scott Sutherland ( 🌦️ 🌩️ 🌀 🌙 🚀 🛰️)‏Verified account @ScottWx_TWN 29 Dec 2018
        Replying to @physicsJ

        That's strange. I played it in VLC, going frame by frame. Here's frames 24, 25 and 26, of the 27th second of the video. Along with the colour change, note how the rotation arrow skips backward. Frame 25 seems to be the same as frame 18 of that second.pic.twitter.com/AYQn0Af4WO

        1 reply . 0 retweets 2 likes
      5. Scott Sutherland ( 🌦️ 🌩️ 🌀 🌙 🚀 🛰️)‏Verified account @ScottWx_TWN 29 Dec 2018
        Replying to @ScottWx_TWN @physicsJ

        For the subsequent glitches (there's maybe 8 of them, total), it always skips back a number of frames. It never seems to be by the same amount, though. Looks like Frame 27 skips to Frame 21, and Frames 29 and 33 both skip back to Frame 23.

        1 reply . 0 retweets 1 like
      6. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @ScottWx_TWN

        I wonder if that's compression from downloading it? Do you see this glitch on Twitter itself? Here's a higher resolution version fyi:https://tinyurl.com/y85u2ev7 

        1 reply . 1 retweet 5 likes
      7. Scott Sutherland ( 🌦️ 🌩️ 🌀 🌙 🚀 🛰️)‏Verified account @ScottWx_TWN 29 Dec 2018
        Replying to @physicsJ

        Ah. There we go. The one in your tweet plays just fine. No glitches.

        1 reply . 0 retweets 1 like
      8. Scott Sutherland ( 🌦️ 🌩️ 🌀 🌙 🚀 🛰️)‏Verified account @ScottWx_TWN 29 Dec 2018
        Replying to @ScottWx_TWN @physicsJ

        As soon as I go to the dropbox page, and either play it there, or play the one I download from there, that's when the glitches show up.

        1 reply . 0 retweets 1 like
      9. Dr. James O'Donoghue‏ @physicsJ 29 Dec 2018
        Replying to @ScottWx_TWN

        Hmm, that's odd! I downloaded it and looked at each frame from 36-40sec and it looks normal. It sounds like something complex to do with video codecs, I'm no expert though

        1 reply . 0 retweets 0 likes
      10. 9 more replies

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