At the #AAS237 conference yesterday I went to a panel discussion on the effect of large constellations of satellites on astronomy from the ground. The thousands of satellites @spacex and others want to launch are a serious problem. 1/n

@SpaceX The launch of so many satellites might change the appearance of the night sky for ever and the trails they leave in astronomers' cameras and the potential for interference with radio telescopes are serious problems 2/n
@SpaceX Those problems are particularly acute for those searching for near-Earth or threatening asteroids, for example, though any large survey of the sky is affected. 3/n
@SpaceX It was good to see @spacex, Amazon's Kuiper project and @oneweb present, and to hear that the latter have dropped their plans from more than 40,000 satellites to 'only' 6372. All the speakers were positive about working together. 4/n
@SpaceX @OneWeb And a lot has been done. All three companies talked about making sure their satellites were fainter than 7th magnitude soon after launch, which would make them invisible to the naked eye and avoid the worst problems for large surveys 5/n
@SpaceX @OneWeb .@spacex satellites launched since August have had sunshields to reduce their brightness, and they change orientation en route to their orbit, which is all good. It was encouraging to hear other companies talking about similar measures. 6/n
@SpaceX @OneWeb But. I remain very concerned. Firstly, we're essentially relying on good will - for these companies to spend their money reducing our problems. No regulation yet compels them to do so and any new operators could ignore astronomy. 7/n
@SpaceX @OneWeb On top of that, all three commercial speakers had latched on to 'mag 7' as a target. Yet, as Tony Tyson from @VRubinObs reminded us, at that brightness a satellite is 40 million times brighter than a typical galaxy in the survey 8/n
@SpaceX @OneWeb @VRubinObs Making up for the presence of thousands of satellites at that sort of brightness probably doesn't mean clever programming or statistical tricks, though they will help. It means running one's survey for longer to get the same scientific return. 9/n
@SpaceX @OneWeb @VRubinObs That means more money will be needed for operations, analysis - and for the staff to do these things. 10/n
@SpaceX @OneWeb @VRubinObs For big projects like @VRubinObs, that means an additional cost of millions of dollars. For smaller projects, which are cash strapped, it means finding funds to pay postdocs and students to keep the show on the road. 11/n
@SpaceX @OneWeb @VRubinObs As this is a cost on the research community caused by commercial entities I asked whether anyone had thought about mitigating it. There was - literally - silence from the commercial reps. 12/n
@SpaceX @OneWeb @VRubinObs It's great that they're taking actions to reduce the effect of their satellites. But if they want to be viewed as collaborators in our science, they should pay to fix the problems they're about to cause. 13/n
@SpaceX @OneWeb @VRubinObs What would be loose change for @spacex or @amazon would be make or break money for most astronomical projects. One of the speakers asked astronomers to do more research - well, research needs funding. 14/n
@SpaceX @OneWeb @VRubinObs @amazon And until someone addresses that, the general tone of the discussion, consisting of diplomatic gratitude and relief that large commercial companies are willing to engage with the problem at all, rather sticks in my craw. 15/15.

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Ok, I’ve told this story a few times, but maybe never here. Here we go. 🧵👇


I was about 6. I was in the car with my mother. We were driving a few hours from home to go to Orlando. My parents were letting me audition for a tv show. It would end up being my first job. I was very excited. But, in the meantime we drove and listened to Rush’s show.

There was some sort of trivia question they posed to the audience. I don’t remember what the riddle was, but I remember I knew the answer right away. It was phrased in this way that was somehow just simpler to see from a kid’s perspective. The answer was CAROUSEL. I was elated.

My mother was THRILLED. She insisted that we call Into the show using her “for emergencies only” giant cell phone. It was this phone:


I called in. The phone rang for a while, but someone answered. It was an impatient-sounding dude. The screener. I said I had the trivia answer. He wasn’t charmed, I could hear him rolling his eyes. He asked me what it was. I told him. “Please hold.”

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The first ever world map was sketched thousands of years ago by Indian saint
“Ramanujacharya” who simply translated the following verse from Mahabharat and gave the world its real face

In Mahabharat,it is described how 'Maharishi Ved Vyasa' gave away his divine vision to Sanjay


Dhritarashtra's charioteer so that he could describe him the events of the upcoming war.

But, even before questions of war could begin, Dhritarashtra asked him to describe how the world looks like from space.

This is how he described the face of the world:

सुदर्शनं प्रवक्ष्यामि द्वीपं तु कुरुनन्दन। परिमण्डलो महाराज द्वीपोऽसौ चक्रसंस्थितः॥
यथा हि पुरुषः पश्येदादर्शे मुखमात्मनः। एवं सुदर्शनद्वीपो दृश्यते चन्द्रमण्डले॥ द्विरंशे पिप्पलस्तत्र द्विरंशे च शशो महान्।

—वेद व्यास, भीष्म पर्व, महाभारत


Meaning:-

हे कुरुनन्दन ! सुदर्शन नामक यह द्वीप चक्र की भाँति गोलाकार स्थित है, जैसे पुरुष दर्पण में अपना मुख देखता है, उसी प्रकार यह द्वीप चन्द्रमण्डल में दिखायी देता है। इसके दो अंशो मे पीपल और दो अंशो मे विशाल शश (खरगोश) दिखायी देता है।


Meaning: "Just like a man sees his face in the mirror, so does the Earth appears in the Universe. In the first part you see leaves of the Peepal Tree, and in the next part you see a Rabbit."

Based on this shloka, Saint Ramanujacharya sketched out the map, but the world laughed