Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The most accurate map for August 21’s total solar eclipse

nasaviz.gsfc.nasa.gov

Post reply on HN
Print view View original

31–40 of 176 posts

Re: The most accurate map for August 21’s total solar eclipse

#31

Post by qwerunf »

nicholas73 wrote: post #28
idlewords wrote: post #24

If you've never seen a total eclipse before and you live in the US, make every effort to see this one! It's not something that you can get the feel of by viewing photos or video. Watching the sun get eaten by a black void activates something deep inside the animal brain. Don't settle for a partial eclipse, do what it takes to get in the path of totality. If you have seen a total eclipse before, then you don't need an…

Is there something special about this total eclipse over others?

It's "relatively" easily accessible for those living in the United States and covers a huge swath of the country.

Many total solar eclipses happen over the middle of the ocean, or at the poles, or in a location that is not as easily accessible.

The next eclipse (after this one) to pass through the United States is in 2024.

Re: The most accurate map for August 21’s total solar eclipse

#32

Post by jessriedel »

Can someone explain why the claimed shadow of the moon is vastly more bumpy than it ever appears in the night sky? Or how to square this with the fact that altitude of the highest and lowest points on the Moon differ by less than 20km, or less than 1% of the diameter? The shadow looks like it has bumps of about 5-10% of the diameter.

Re: The most accurate map for August 21’s total solar eclipse

#34

Post by davidw »

JPKab wrote: post #8
wyldfire wrote: post #2

I heard from a co-worker who plans to travel to Oregon that some of the hotel rooms in the path of the umbra are sometimes > 2-3k USD for the night(s) prior to the eclipse.

I think Oregon is a bad spot to view it. The weather (yes, even in summer) is too unpredictable and it's too close to populated coastal areas. Wyoming is the way to go, or western Nebraska. Don't expect to get hotels, but camping on a rancher's land is easy, and the arid climate in the summer minimizes chances of cloud cover.

Errr, east of the Cascades, Oregon is pretty dry and sunny. Look at the satellite today, for instance:

http://weather.cod.edu/satrad/exper/?parms=northwest-02-48-0

Perfect example of the Cascades blocking the crap.

That said, it looks like things are going to be a complete and total mess here in central Oregon with all the people converging on this area.

Re: The most accurate map for August 21’s total solar eclipse

#35

Post by 21 »

jessriedel wrote: post #32

Can someone explain why the claimed shadow of the moon is vastly more bumpy than it ever appears in the night sky? Or how to square this with the fact that altitude of the highest and lowest points on the Moon differ by less than 20km, or less than 1% of the diameter? The shadow looks like it has bumps of about 5-10% of the diameter.

The effect was probably exaggerated, otherwise you would just see a smooth circle.

Re: The most accurate map for August 21’s total solar eclipse

#36

Post by petsfed »

JPKab wrote: post #8
wyldfire wrote: post #2

I heard from a co-worker who plans to travel to Oregon that some of the hotel rooms in the path of the umbra are sometimes > 2-3k USD for the night(s) prior to the eclipse.

I think Oregon is a bad spot to view it. The weather (yes, even in summer) is too unpredictable and it's too close to populated coastal areas. Wyoming is the way to go, or western Nebraska. Don't expect to get hotels, but camping on a rancher's land is easy, and the arid climate in the summer minimizes chances of cloud cover.

Camping on a rancher's land with permission is easy. But given the expected crowds, friends in e.g. Glendo (population ~200) plan to be out enforcing their property rights against the anticipated tens-of-thousands of out-of-towners. So be smart, camp on public land. Otherwise you'll likely get shot.

Re: The most accurate map for August 21’s total solar eclipse

#37

Post by maxxxxx »

JPKab wrote: post #27
maxxxxx wrote: post #11

Earlier quoted context omitted.

What do you think of Grand Teton? I will in Yellowstone that week. I am not sure if we should go do Grand Teton or Nebraska for the eclipse. Ideally I want to hike somewhere for a few miles to avoid the crowds.

The Grand Tetons/Yellowstone are super packed on normal summer days. Jackson Hole is super expensive on normal summer days. Probably gonna have a hard time.

I have a campsite reserved in Yellowstone and would drive South. I guess a good plan would be to pick a trail and go there at night so you are already on thew trail before the crowds come. Not sure about the weather though.

Re: The most accurate map for August 21’s total solar eclipse

#39

Post by bradleyjg »

pavel_lishin wrote: post #17
learc83 wrote: post #13

Earlier quoted context omitted.

I don't see the point of booking something without knowing the weather unless you don't care about throwing it away and going somewhere else. My initial plan was to book several hotels in different areas, but it seems like every hotel inside the path of totality requires a 2 week notice to cancel (and this was months ago). Since I'm about 1.5 hours from the path of totality in Georgia, my current plan is to drive out…

I'm in New York. I'm more than 1.5 hours away from the totality, so I'm going to have to head south and hope - although, I'm in the somewhat enviable position of just being able to sleep in a car... as long as someone cracks the window and leaves me a bowl of water. On the other hand, the totality will pass in the very early afternoon, so I can probably just head back once it's over.

Are you thinking Greenville? Columbia? Somewhere off I-95?

Re: The most accurate map for August 21’s total solar eclipse

#40

Post by ErrantAstro »

jessriedel wrote: post #32

Can someone explain why the claimed shadow of the moon is vastly more bumpy than it ever appears in the night sky? Or how to square this with the fact that altitude of the highest and lowest points on the Moon differ by less than 20km, or less than 1% of the diameter? The shadow looks like it has bumps of about 5-10% of the diameter.

There are two principal factors at work here.

The first is the eccentricity of the lunar orbit - 0.0549 which means that depending on where in the lunar orbit the eclipse occurs, the moon is closer or further away meaning the apparent size ratio between the Sun and Moon varies. In fact - it's even possible to have an eclipse where the Sun's limb is visible around the edge of the Moon at totality - this is called an annular eclipse. [1]

The second factor is that the Moon is lumpy! The depressions caused by craters and valleys means that totality, as defined as when the Moon completely occults the Sun's disc, varies according to where in the path of totality you are. Parallax effects move the Sun with respect to the observed position of the Moon, so the Sun will peek through the valleys/craters earlier or later depending on your latitude. This lumpiness actually creates one of the most spectacular features of a total solar eclipse, the "diamond ring" effect - I had the rare privilege of seeing this in the 1999 eclipse that crossed south-west England and northern France - a mere teenager but the image is burned into my brain. [2]

Other minor factors come into play which add to why the shape of the polygon changes across the track - the Earth is a spheroid, not a flat plane so the ratio of Sun:Moon coverage varies along the track; also the Moon is still gently turning as it orbits in a manner called libration - while tidally locked to face the Earth, the Moon still rotates marginally faster or slower along its orbit. [3]

The effects of the compensation for totality variation are shown in the second half of the video past ~1:20.

[1] https://en.wikipedia.org/wiki/Solar_eclipse#/media/File:Annu...

[2] https://youtu.be/WBIyYCdwX1k?t=254

[3] https://en.wikipedia.org/wiki/Libration#Lunar_libration

Post reply on HN