#Tag · 𑐴𑐶𑐟𑐶

Phil Stooke @PhilStooke@mastodon.social · last month

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I answered my first map question in a separate post. Back to Herschel: his map has no coordinates but coordinates can be approximated. I projected the Herschel map into a cylindrical projection and then into two equator-centred azimuthal projections making the best match I could to modern coordinates. My intention was to take a variety of historical and recent maps in different projections and display them all in a common format for comparison. #maps #Mars #Herschel

William Herschel's map of Mars reprojected into an equator-centred pair of azimuthal projections, roughly matched to modern coordinates.

Phil Stooke @PhilStooke@mastodon.social · last month

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Here is Herschel's actual map (left). I compare it with a mid-20th Century map in the same projection (azimuthal, extending from the south pole at centre to the mid-latitudes in the northern hemisphere). There's no coordinate grid but it vaguely resembles the more modern map. It's the first map of Mars, but not the first map of another planet. Anyone care to speculate who made the first map of another planet, and which one? #maps #Mars #Herschel

William Herschel's 1784 map of Mars (left) and a mid-20th Century map in the same (approximate) geometry (right). I will identify the more modern map when we get to it in the sequence.

Phil Stooke @PhilStooke@mastodon.social · last month

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The next stop on our history of Mars mapping is the German astronomers Beer and Mädler. Working in the 1830s and 40s, they took Mars maps a significant step further, establishing a coordinate system and a prime meridian which is essentially what we use today. Here is the map made from observations in 1830 (published 1831) when the southern hemisphere was visible (as for Herschel). The south pole in in the middle, 30 north at the outer edge. #maps #Mars #Beer #Mädler

A map of Mars made in 1830 by German astronomers Beer and Mädler. it shows the south pole at the centre and 30 degrees north at the outer edge in an interrupted azimuthal projection.

Phil Stooke @PhilStooke@mastodon.social · last month

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In 1841 Beer and Mädler published a map of the whole planet after the north pole became visible later in the 1830s (it all depends which pole is tilted towards us when Mars is closest to Earth). They stuck with polar projections which led them into a clumsy mistake. I'm just glad I'm not the only one - you can't be out there as much as I am without making public mistakes. Look at the longitude of feature 'f' (= Syrtis Major) in the two hemispheres. One (north) is wrong. #maps #Mars #Beer #Mädler

Mars mapped by Beer and Mädler in 1841. The whole planet is shown in two pole-centred hemispheres. Splitting the map at the equator caused a mistake. A feature labelled 'f' (it is what we would call Syrtis Major) is at about longitude 70, but in their northern hemisphere it is at about 100 degrees. Mädler drew the map, and he must have kicked himself when he noticed.

Daniel Pomarède @pomarede@mastodon.social · 2 months ago

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Zebra Rock, a mysterious rock with black and white stripes, captured by Perseverance in Stereo3D

To go 3D: eyes' lines of sight parallel/left image for left eye/right image for right eye

Calibrated images by the Mastcam-Z team at Arizona State Univ., Sol 1268, Sep. 13, 2024

#Mars #Perseverance #ZebraRock #FreyaCastle #3D #Stereo3D #stereoscopy #geology #planetaryscience #Mars2020 #rock #rocks #solarocks #science #Stem #astrodon #Mastcam #MastcamZforall #photography

Daniel Pomarède @pomarede@mastodon.social · 2 months ago

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An asteroid’sdestruction may have given Mars rings, then moons

Scientists simulated a situation that may offer an improved explanation for how the Red Planet ended up with small Phobos and tiny Deimos.

https://www.nytimes.com/2024/11/22/science/mars-moons-asteroids-rings.html?unlocked_article_code=1.ck4.3uM1.EupDU6iZI7Uo&smid=url-share&et_rid=1080503712&et_cid=5442065

Credits video: Jacob Kegerreis, et al./NASA Ames

#Mars #Phobos #Deimos #science #Astrodon #STEM #space #rings #NYTimes #news