All Things Space

[ShinkanPo]

According to a How the Universe Works program on The Science Channel, over 55% of stars exist in two or three star systems. This means our system isn't considered normal. We are also in a much less dense part of the Milky Way than most stars which makes us less subject to the radiation from novas and supernovas.

To me this seems to lower the number of stars and systems that could harbor life as they would also likely be in a less dense area.

Very interesting is this what Enrico Fermi mentioned in his Fermi Paradox?

 

[rj144]

You're leaving out the part where the solar system was born in a cloud of such dust and gas and radiation. Then it migrated to its current position over billions of years. Nothing stops other systems from doing the same thing. It was in a much denser region in the past. Add to that there are billions and billions of solar systems, so even if you eliminate 99.99 percent of them, it still leaves a lot that could harbour life.

Has it migrated though? I've yet to hear any definitive evidence to suggest it has.

 

[Andy Capp]

Has it migrated though? I've yet to hear any definitive evidence to suggest it has.

Definitively? As in, with absolute certainty? Perhaps not. However, it is first of all a logical impossibility for the solar system to have formed in its present location outside any of the main spiral arms of the galaxy. There is no material from which to form. The vast majority of star forming regions in our galaxy are in the spiral arms. There are several mechanisms for such an out-migration. I don't know that there is any definitive proof but it is currently the generally accepted explanation (pending future findings, of course) of how the Sol system came to be so far away from any star forming region. Note also, I'm sure there's been statistical analysis up the great wazoo on the collective motions of stars around the centers of galaxies, but I'd bet there's much we don't know about how individual stars move around their host galaxies.

And then there's this:
EDIT:
Falling out of a Cluster: The history of the Sun
While we can’t do more than guess at the Sun’s original orbital position, we know that today it takes about 135 million years for the Sun to orbit the galaxy. Let’s assume for a minute that the Sun emerged from the center of of that cluster. This would put it in a position to watch some of its nursery mates race ahead around the galaxy, take less time to orbit, while other of its nursery mates slowly fell behind, taking longer to orbit (and a few just explode themselves into oblivion as supernovae). After a few orbits and a few hundreds of millions of years, these differences in speed caused the fastest (and slowest) stars to fall out of the cluster, as their positions no longer made it possible for the casual observer to match them up with their cluster of origin. Over time, differences in orbital velocities drew more and more of the stars away from their siblings. Eventually, it became impossible to tell exactly which stars made up those sibling stars to the Sun.

The Sun, like its sisters and brothers, simply fell out of the cluster as it raced around the galaxy, just as a runner might fall away from the pack.

We are an orphan system, alone in the galaxy. Unlike the majority of stars, our Sun has no companion. Having escaped the chaos of our home, we are now simply alone.

Earth has water older than the Sun
But the interstellar clouds where Sun-like stars are currently forming — and thus, presumably, the material from which the Sun formed — have a higher proportion of heavy water compared to the current Solar System. This is because these clouds are subject to the continuous bombardment of cosmic rays, which tend to favour the inclusion of deuterium. Therefore, the authors concluded, the young Sun’s radiation was insufficient to account for the amount of heavy water seen in the Solar System today, and some must have existed before. They estimate that somewhere between 30% and 50% of the water in Earth’s oceans must be older than the Sun.

 

[rj144]

Definitively? As in, with absolute certainty? Perhaps not. However, it is first of all a logical impossibility for the solar system to have formed in its present location outside any of the main spiral arms of the galaxy. There is no material from which to form. The vast majority of star forming regions in our galaxy are in the spiral arms. There are several mechanisms for such an out-migration. I don't know that there is any definitive proof but it is currently the generally accepted explanation (pending future findings, of course) of how the Sol system came to be so far away from any star forming region. Note also, I'm sure there's been statistical analysis up the great wazoo on the collective motions of stars around the centers of galaxies, but I'd bet there's much we don't know about how individual stars move around their host galaxies.

And then there's this:
EDIT:
Falling out of a Cluster: The history of the Sun
While we can’t do more than guess at the Sun’s original orbital position, we know that today it takes about 135 million years for the Sun to orbit the galaxy. Let’s assume for a minute that the Sun emerged from the center of of that cluster. This would put it in a position to watch some of its nursery mates race ahead around the galaxy, take less time to orbit, while other of its nursery mates slowly fell behind, taking longer to orbit (and a few just explode themselves into oblivion as supernovae). After a few orbits and a few hundreds of millions of years, these differences in speed caused the fastest (and slowest) stars to fall out of the cluster, as their positions no longer made it possible for the casual observer to match them up with their cluster of origin. Over time, differences in orbital velocities drew more and more of the stars away from their siblings. Eventually, it became impossible to tell exactly which stars made up those sibling stars to the Sun.

The Sun, like its sisters and brothers, simply fell out of the cluster as it raced around the galaxy, just as a runner might fall away from the pack.

We are an orphan system, alone in the galaxy. Unlike the majority of stars, our Sun has no companion. Having escaped the chaos of our home, we are now simply alone.

Earth has water older than the Sun
But the interstellar clouds where Sun-like stars are currently forming — and thus, presumably, the material from which the Sun formed — have a higher proportion of heavy water compared to the current Solar System. This is because these clouds are subject to the continuous bombardment of cosmic rays, which tend to favour the inclusion of deuterium. Therefore, the authors concluded, the young Sun’s radiation was insufficient to account for the amount of heavy water seen in the Solar System today, and some must have existed before. They estimate that somewhere between 30% and 50% of the water in Earth’s oceans must be older than the Sun.

Couldn't the differential rotation of the galaxy also explain moving away from a denser portion of the Milky Way?

But, I do understand your main premise of the sun's environment changed over time.

 

[Andy Capp]

Couldn't the differential rotation of the galaxy also explain moving away from a denser portion of the Milky Way?

But, I do understand your main premise of the sun's environment changed over time.

Yes, like I said, you can debate the mechanism ad nauseam. I disagree on that score with the article but you can't hold that against the printed page.

It turns out a ginormeous number of stars form in binary (or greater) groups and that, out of that number, there are quite a few ways that systems can be perturbed to cause individual stars to be flung out on their own. I favour this as the most likely mechanism based upon what little we know so far. However, it turns out, the likelihood of "Nemisis" a black dwarf binary to Sol has increased just a tiny bit with some observations of dwarf planets. I still place it an outside 3rd.

 

[Andy Capp]

I wonder if our species is just one Hyper Nova away they said some Hyper Novas can cause mass extinctions!

Our species is 1 "a whole lot of things" away from being effectively wiped out. Gamma Ray burst, nearby nova, pick a kind, undetected large body incoming from off the plane of the solar system, super volcano eruption, and I'm sure I've left out several. Seems to have escaped people's attention.

 

[ralphc1]

Our species is 1 "a whole lot of things" away from being effectively wiped out. Gamma Ray burst, nearby nova, pick a kind, undetected large body incoming from off the plane of the solar system, super volcano eruption, and I'm sure I've left out several. Seems to have escaped people's attention.

We have beaten the odds so many times to get to this point. Any number of things could have changed the course of history. If the Earth/Thera collision creating the moon theory is correct, just a few degrees different angle and the earth could be another asteroid belt.

 

[ShinkanPo]

We have beaten the odds so many times to get to this point. Any number of things could have changed the course of history. If the Earth/Thera collision creating the moon theory is correct, just a few degrees different angle and the earth could be another asteroid belt.

So many posibilities and in this universe I end up with a microsoft dick.

 

[rj144]

Yes, like I said, you can debate the mechanism ad nauseam. I disagree on that score with the article but you can't hold that against the printed page.

It turns out a ginormeous number of stars form in binary (or greater) groups and that, out of that number, there are quite a few ways that systems can be perturbed to cause individual stars to be flung out on their own. I favour this as the most likely mechanism based upon what little we know so far. However, it turns out, the likelihood of "Nemisis" a black dwarf binary to Sol has increased just a tiny bit with some observations of dwarf planets. I still place it an outside 3rd.

Or a somewhat rogue star like Sholtz's star.

 

[Andy Capp]

Very interesting is this what Enrico Fermi mentioned in his Fermi Paradox?

The Fermi paradox has been criticized as being based on an inappropriate use of propositional logic. According to a 1985 paper by Robert Freitas, when recast as a statement in modal logic, the paradox no longer exists, and carries no probative value.[19]

 

[V-2]

Pioneer 10 & 11 are essentially ghost probes floating through space at this point and have been for quite some time. P11 gave out and sent its final transmission on September 30, 1995 while its twin soldiered on, sending a final received signal on January 23, 2003. How the Voyager(s) continue sending back useful data from interstellar space with their remaining working instruments four decades on is pretty astonishing.

A little bit of background information on the relatively brief history of outer planet exploration. These sort of missions actually don't occur very often at all and ordinarily take a very long time to get off the ground.

NOTE: The Ulysses probe was a joint project between NASA and ESA (European Space Agency) in the 1990s, primary focus was that of solar satellite. So while it did pass Jupiter on a loop back around en route to the Sun, it isn't considered a 'proper' outer planet mission.

Pioneer (NASA Ames) [1972-1997]

Just as the name would suggest, these were the first spacecraft(s) to travel through the asteroid belt and make successful flyby's of Jupiter and Saturn. A true feat to be sure, although they were almost something of a test run compared to what would follow. Officially decommissioned in 1997, heard from for the last time in 2003.

Voyager (NASA JPL) [1977-present]

Humanity's space probes. The first and only to have flown by and surveyed all four of the outer gas giants in one mission, the only spacecraft (Voyager 2) that's been to Uranus and Neptune to date and the first to ever cross into Interstellar space (Voyager 1). The amount of scientific data acquired from the probes by 1989 alone was enough to fill 6,000 editions of Encyclopedia Brittanica.

What's more: it's still an ongoing, active mission four decades later, still transmitting data with the instruments that are operational although one-way communication now has a 17-plus hour delay through the Deep Space Network as Voyager 1 & 2 are over 20 and 18 billion kilometers away from Earth, respectively. No other space exploration mission beyond the moon boasts anywhere near the same level of achievement.

Galileo (NASA JPL) [1989-2003]

The first Jupiter orbiting spacecraft and came attached with a separate atmospheric entry probe intended to gather as much as possible in a very finite amount of time (i.e. before it got vaporized). Galileo successfully went into orbit in December 1995 after encountering two asteroids en route but had a more specified focus on various Jovian moons. Sustained significant radiation damage and lost capabilities over the course of its mission before (plan) crashing into Jupiter's atmosphere.

Cassini (NASA JPL) [1997-present]

The only orbiting probe sent specifically to study the Saturnian system in detail along with a Titan moon lander (Huygens) in tow that was developed by the ESA, though it lasted only 90 minutes before losing power. Cassini arrived and went into orbit in 2004 and has been building on the Pioneer and Voyager observations ever since. Craft is still in decent health and a currently active mission, expected to last through September 2017.

New Horizons (NASA Goddard) [2006-present]

Kuiper Belt probe that made a little bit of noise during the Summer of 2015 when it completed its flyby of the dwarf Pluto. Incidentally, Voyager 1 could've went by it decades ago but due to the limited navigational ability at the time, JPL had to decide between that or a closer look at Saturn's moon of Titan, which sent it on a trajectory above the plane of the solar system and out into Interstellar space.

Our species is 1 "a whole lot of things" away from being effectively wiped out. Gamma Ray burst, nearby nova, pick a kind, undetected large body incoming from off the plane of the solar system, super volcano eruption, and I'm sure I've left out several. Seems to have escaped people's attention.

Not just that, but the way we - as humans - still treat each other is so shitty and depressing sometimes. When you let yourself catch that Science bug, it has a way of influencing your entire perspective on life and even worldview if you go deep enough on it.



^ Legendary shot taken by Voyager 1 in 1990 btw, without a doubt the greatest space exploration mission ever undertaken IMO for what the twin spacecraft achieved and how long they've survived into deep space. Launched in the Summer of '77 and still going as an active mission 40 years on even as instrument panels start to give out and are shutdown to preserve power.

 

[rj144]

You guys ever play around with the program/simulation/game Space Engine? It's really cool for exploration of universe. It's amazingly well done too.

Video from the program:

 

[Jack Reacheround]

Yup, and it will be replaced by the Orion hopefully by 2020s by the early NASA will have its first Manned space launch again.

Isn't Orion the nuclear blast powered spaceship they were trying to build, or at least thinking about building, a long time ago, like in the 60s? If so, awesome.

 

[Monkadelic]

I'm sure I posted this somewhere on here already, but have it again anyway.



I'm fairly certain Carl Sagan could talk me off.

 

[rj144]

I was fooling around SpaceEngine today. It really is quite amazing for space buffs. I took these pics from the simulation today:

I know it's only a program, but those pics look pretty cool.

 

[Bunk Moreland]

Sweet