My niece has been visiting from Greenville, SC for a few days and when I asked her if she was excited about the total eclipse in August she didn't know what I was talking about. She said whatever it was she wouldn't be able to take off from work to watch it. I told her that she couldn't avoid it unless she was in a building without windows because the center of the track comes just a short distance from Greenville. Then she got her phone out and googled it and that's when she realized what a big deal it was.

 

I told her I was going to have to drive hours to experience it and she was lucky that it's coming to her neighborhood.

My niece has been visiting from Greenville, SC for a few days and when I asked her if she was excited about the total eclipse in August she didn't know what I was talking about. She said whatever it was she wouldn't be able to take off from work to watch it. I told her that she couldn't avoid it unless she was in a building without windows because the center of the track comes just a short distance from Greenville. Then she got her phone out and googled it and that's when she realized what a big deal it was.

 

I told her I was going to have to drive hours to experience it and she was lucky that it's coming to her neighborhood.

 

You're right, Prof, it's a biggie. I'm trying to let everyone that is unaware of it just what an opportunity they have. It's been 99 years since such a large swatch of America has had the opportunity to view a total eclipse.

Ever since I was a kid I knew that the next nearest star, after the Sun was Proxima Centauri. PC is a mere 4.246 LY( in our backyard in astronomical terms) but because it is a small red dwarf and quite faint, it can't be seen with the naked eye. Contrast this to Betelguese, which is easily visible to the naked eye in the fall and winter despite being nearly 643 LY away.

 

As I said, Proxima Centauri is the nearest-known star to the Sun and is a red dwarf in the the constellation Centaurus. It makes up the third component in the Alpha Centauri binary star system. While PC is the nearest known star to our Sun it is within the realm of possibility that there could be one or more as yet undetected substellar brown dwarfs that lie closer.

 

Some stats about PC. It has about 1/7 the Sun's diameter , 1/8 the Sun's mass, and is about 40 times more dense than the Sun.

 

Proxima b is a planet that orbits PC at a distance of about 4.7 million miles every 11.2 Earth days and has an equilibrium temperature that is estimated to be within the range where water could exist on its surface, placing it within the habitable zone of PC. Could we have extraterrestrial neighbors in our astronimical backyard, so to speak?

 

Before I get you too excited about a flyby to proxima b or PC , let me do a couple of calculations. Yes, as far as astronomical distances are concerned, Proxima Centauri is close---REALLY CLOSE ! However, let's see what non-nuclear, conventional propulsion technologies would allow us to do.

 

PC is currently moving towards us at 22.4 km/s . After 26,700 years it will reach its "closest" approach to Earth at 3.11 LY, before receding.

 

Let's say we wanted to fly a conventional spacecraft similar to Voyager I to the planet proxima b, which orbits PC. If we flew at, say, 38,000 mph relative to the Sun in the direction of the star, we would reach the planet in about 73,775 years!!! And folks, we are talking about the next nearest star to us!!!

 

For the purposes of interstellar travel, I hope we develop some amazing and almost unimaginable ways to propel spaceships through interstellar space within the next century. I believe that those who will come after us will oneday conquer these interstellar distances and will explore intergalactic space with the same zeal that Columbus, Balboa, Drake, and da Gama explored the New World. Future space travelers will just have a hellava lot better tools to work with.

Our neighboring star, Proxima Centauri, as seen by Hubble:

 

Happy Aphelion Day! Today, Earth is at its farthest point from the sun that it gets all year.

Happy Aphelion Day! Today, Earth is at its farthest point from the sun that it gets all year.

 

Happy Aphelion Day to you, my friend. Thank you as always for contributing to the thread.

Picked up a shirt last time I was at the planetarium similar to this except it doesn't say "Appalachian Eclipse 2017." I may try to check out another planetarium before August and see if I can find another shirt.

 

Last night, I was pondering what Galileo must have thought the first time he focused his little telescope on Jupiter and saw this:

 

 

His incontrovertible discovery of celestial bodies orbiting something other than Earth dealt a serious blow to the then-accepted Ptolemaic world system, or the geocentric theory in which everything orbits around Earth.

A rare triple transit of Jupiter by Callisto, Io , and Europa captured by Hubble in 2015.

 

How big is our universe? I ponder this question all the time. I know it's big...REALLY BIG , and getting bigger all the time. We know the universe is about 13.8 billion years old, thus all the light that we see in the "observable" universe took 13.8 billion years to reach us. But since the universe is ever expanding the current distance to the edge of the observable universe is 46 billion LY , or about

276,000,000,000,000,000,000,000 miles.

 

Imagine for a minute that a photon of light is emitted from the edge of the observable universe. While that photon has been travelling through space, the universe has expanded. We have moved away from the point where the light was emitted, and it has moved away from us!

 

Though the light might have only travelled for 13.8 billion years, the distance from us to the point it came from is, at present, 46 billion light years!

 

So how big is our universe? Well we don't really know, but it's big. So big that even light hasn't had time to cross it in nearly 14 billion years! And it's still getting bigger all of the time.

Four billion years from now, the Earth will no longer be able to call the Milky Way home. Why? Because our home galaxy is on course for a head-on collision with its large spiraling neighbor galaxy, Andromeda. The two galaxies will not survive,at least in the form we know them today.

 

Our solar system is actually gonna outlive our galaxy. While the Sun will have not yet become a red giant by 4 billion A.D., it will have become bright enough to scorch the Earth's surface. Whatever life forms, if any, that still exist at that time will be treated to one hellava light show and some incredible cosmic choreography!!!

 

The Milky way and Andromeda are currently about 2.5 million LY apart and are racing towards each other at 250,000 mph. Even at that speed, it'll be 4 billion years until they engage each other in galactic intercourse and eventually give birth to a new elliptical galaxy. The two galaxies will collide head-on and fly through one another, leaving gassy, starry tendrils in their wakes. For eons, the pair will continue to come together and fly apart, scrambling stars and redrawing constellations until eventually, after a billion or so years have passed, the two galaxies merge. Our solar system will then have a new cosmic address- a giant elliptical galaxy formed by the collision and subsequent merger of the two spiral galaxies.

 

Since I am always looking for the good news in anything, the good news here is that stars are so far apart that even though galaxies are colliding, the probabilities of stellar collisions are small. So the sun and its planets will likely survive the birth of the new galaxy, though Earth will no longer be able to call the Milky Way home. And Earth will no longer live in a spiral galaxy, it will be elliptical and will probably look quite reddish in the sky.

 

If that wasn't enough, there's a pretty good probability that a third smaller, nearby galaxy may get sucked into this cosmic free-for-all, making it a cosmic threesome, of sorts.

 

I know this sounds odd, but as an space nerd, this would be the ultimate spectacle to observe. It makes me kinda sad that I won't be here to witness this galactic show of shows four billion years from now.

If you could be on Earth close to 4 billion years from now you might see something like this as Andromeda begins to tug and deform our beloved Milky Way.

 

[ATTACH]62673[/ATTACH]

I'll try this again. Andromeda and MW in about 3.75 billion yrs , as viewed from Earth.

 

July 4, 1054 --- Some 722 years to the day before America gained it's independence, there was a quite a sight that appeared in the sky that must have rivaled the rockets red glare and bombs bursting in air that occurred seven centuries later during the American Revolution.

 

What astronomical event occurred, you ask? Of course, it was Supernova 1054, as it is now known. It was spotted by Chinese astronomers in the Constellation Taurus. In the nearly 1600 year period from around 530 B.C. to about 1060 A.D. , Chinese star gazers recorded at least 75 supernovae. But there was something quite special about this particular explosion. The magnitude of the 1054 star was unusually large.

 

The exploding star appeared four times brighter than Venus in our sky and was visible in daylight for 23 days . It remained visible in the night sky for 653 days.

 

There were also accounts of this supernova by astronomers in the Arab world and also by Indians in North America. Of course, as many of you know, the remnants of those stellar fireworks that were observed 963 yrs ago gave birth to what we know today as the Crab Nebula!!!

 

 

Ever since I was a kid I knew that the next nearest star, after the Sun was Proxima Centauri. PC is a mere 4.246 LY( in our backyard in astronomical terms) but because it is a small red dwarf and quite faint, it can't be seen with the naked eye. Contrast this to Betelguese, which is easily visible to the naked eye in the fall and winter despite being nearly 643 LY away.

 

As I said, Proxima Centauri is the nearest-known star to the Sun and is a red dwarf in the the constellation Centaurus. It makes up the third component in the Alpha Centauri binary star system. While PC is the nearest known star to our Sun it is within the realm of possibility that there could be one or more as yet undetected substellar brown dwarfs that lie closer.

 

Some stats about PC. It has about 1/7 the Sun's diameter , 1/8 the Sun's mass, and is about 40 times more dense than the Sun.

 

Proxima b is a planet that orbits PC at a distance of about 4.7 million miles every 11.2 Earth days and has an equilibrium temperature that is estimated to be within the range where water could exist on its surface, placing it within the habitable zone of PC. Could we have extraterrestrial neighbors in our astronimical backyard, so to speak?

 

Before I get you too excited about a flyby to proxima b or PC , let me do a couple of calculations. Yes, as far as astronomical distances are concerned, Proxima Centauri is close---REALLY CLOSE ! However, let's see what non-nuclear, conventional propulsion technologies would allow us to do.

 

PC is currently moving towards us at 22.4 km/s . After 26,700 years it will reach its "closest" approach to Earth at 3.11 LY, before receding.

 

Let's say we wanted to fly a conventional spacecraft similar to Voyager I to the planet proxima b, which orbits PC. If we flew at, say, 38,000 mph relative to the Sun in the direction of the star, we would reach the planet in about 73,775 years!!! And folks, we are talking about the next nearest star to us!!!

 

For the purposes of interstellar travel, I hope we develop some amazing and almost unimaginable ways to propel spaceships through interstellar space within the next century. I believe that those who will come after us will oneday conquer these interstellar distances and will explore intergalactic space with the same zeal that Columbus, Balboa, Drake, and da Gama explored the New World. Future space travelers will just have a hellava lot better tools to work with.