Mechanical, intentional interstellar travel is unlikely since the distances are far too great to imagine. The best anyone could achieve is interplanetary travel within one’s own solar system. Therefore, if we pass the buck and say life didn’t start here but started somewhere else and arrived here, it would have had to arrive on a rock or asteroid as a microbe and somehow survive a fiery entry through Earth’s atmosphere and it would have had to survive the vacuum and temperature extremes of space. If the rock came from outside the solar system it would have had to survive a long, long time.
Since both the Moon and Mars would require a carefully constructed closed airtight environment or else people will die, I’d take the Moon because it’s easier to leave the Moon and go back to Earth if something starts to go wrong. On the other hand, it’s not so easy to leave Mars and go back to Earth.
After awhile, walking on the moon got old. It cost a whole lot of money and there wasn’t much to do there. The Vietnam war was sucking the budget. We were sending men up there to kick around the dust and rocks, drive rovers around, and it – as I said – cost a lot. Can you give me a good reason to go back?
I don’t think this scientific quest detracts from our appreciation for all the wonderful things we have here on Earth.
You’re right. We need to do both.
However, just why are scientists “so obsessed” with “finding the smallest amount of life on another planet” in the first place, and why are people taking life for granted here on Earth and destroying it?
First, the searching for life in space boils down to an ancient feud between Science and Religion. Galileo (1564-1642), father of modern physics, astronomy, cosmology, mathematics and philosophy, was put on trial by the Catholic Church and convicted. This has never been forgiven.
We spend billions of dollars listening 24/7 for repeating radio waves, sending rovers to drill rocks on Mars, search the nearby stars for signs of “Earth-like” planets, and so on just to have at least some evidence that life has evolved on some other planet in the galaxy or moon in our solar system. It’s such an important endeavor that finding an alien and a UFO from space would delight scientists. If only. Unfortunately, we don’t even have a fossil of a microbe from space. No evidence at all.
We have no proof life exists anywhere in the universe other than Earth. Given a planet with the right conditions, life can spring from matter and eventually evolve into something greater. No God required. It’s the wet dream of science, but still an unproven theory.
Second, people taking life for granted here on Earth and destroying it because – even in our schools – children are being brainwashed to believe the Earth was created 4,000 years ago and not 4.5 billion years ago, and that God created life on Earth and all life and things on Earth are meant for the descendants of Adam and Eve to rule over and enjoy. That mentality drives people not to care about what we do to Earth.
Proxima Centauri, is our nearest star, about 4 light years away.
A light year is the distance light travels in one year, or 9,460,730,472,581 kilometers. That’s 9.46 trillion kilometers, or about 5.88 trillion miles.
The fastest space ship we ever built was the Juno spacecraft, which in 2016 broke all speed records in space with a gravity assisted acceleration up to 164,700 mph.
The problem with going much faster than that is General Relativity and propulsion. Even with all the fuel in the solar system, it would still take an infinite amount of fuel to approach the speed of light. There’s no warp speed or aliens that have somehow “broken” the laws of physics. You can’t approach the speed of light.
If, however, you could go, say 40 times faster than Juno (there’s no existing technology that would come anywhere near this speed), you’d be going about 6.58 million miles an hour. That’s a hypothetical but impossible speed by either humans or space faring aliens, but none the less, for the sake of argument, let’s say you could go that fast.
Light travels at 670,616,629 miles per hour (as a layman and lazy American I think in miles more easily). So your space craft is amazingly, impossibly, traveling slightly less than 1% the speed of light. We’ll round it up for arguments sake. You’re going now 6.7 million miles an hour. Don’t crash into an asteroid at that speed!
How long would it take to make the trip to Proxima Centauri 4 light years away? Well, if you were going 1% the speed of light (6.7 million miles an hour) it would take you 400 years to reach the nearest star.
Unfortunately, you can’t just get up and go 6.7 million miles an hour. You’ve got to build up speed, which conceivably would take years burning some kind of fuel source that would weigh as much as the Moon because you’d need so much of it (which would slow your acceleration). The problem is the faster and longer you want to burn fuel, the more fuel you need, which increases your weight and decreases your acceleration. Remember, also, as you approach any percentage of the speed of light at all, the amount of fuel required to accelerate your spacecraft any faster begins to increase exponentially because of the law of General Relativity.
At the other end of the trip you’d need the same time and fuel to slow down so you don’t overshoot your target.
People have thought about using light propulsion. From somewhere in Earth orbit, shooting a powerful laser at a reflector at the back of the outgoing spaceship. It would be slow, but eventually it would increase in speed. They’d still need fuel at the other end to slow down.
It’s difficult to know how to figure in that acceleration and deceleration process, so I usually, for the sake of argument, just double the time, which probably isn’t far off.
That would mean it would take you about 880 years to start out, accelerate to 6.8 million miles per hour, and then slow down at the other end. That’s how long it would take to reach our nearest star.
As far as we know, there’s not even any interesting planets over there. If you want to go somewhere more interesting you’d probably have to go farther out in a different direction to the Trappist-1 system, which is 40 light years away.
That would only take you 8,000 years each way. We’re talking eight thousand years. You’d need a generational spacecraft, where hundreds of people lived and died for thousands of years before they reach where they’re going. Would these descendants of the original pioneers have any idea what to do when they got there? Would they resent being in space because their ancestors decided they should be? Would the spacecraft hold up and not fall apart after 8,000 years of usage? How would they have enough food and water?
Depressingly, these are only the closest stars, right around our neighborhood. There are many more stars in our local group, and billions more in the galaxy, and millions of galaxies.
All we can do is watch them, study them, wonder about them and so on. We will, however, never be able to visit them, and those aliens out there unable to visit us.
Essentially, without going into technicalities, a full-moon rises at the same time the sun sets. So a full-moon always rises at the same time the sun sets, or within a few minutes either way. That’s why it’s a full moon, because it’s facing the sun directly and therefore the moon will be rising in the East and the Sun will be setting in the West.
Sun set times change, as you know. Some times of the year, winter for example, the sun sets earlier and rises later, so we have shorter days. In the late spring early summer the sun sets later and rises earlier, so the days are longer.
But the full moon rises at sunset. There are some technical issues, like when exactly is the Moon full, but I’m just giving you the simple answer. As the full moon continues to rise the sky will grow darker because the sun already went down.
In this image the full moon rose, but was concealed by a hill. The photographer caught this shot as it rose above the hill and the sky was already darkening.
The far side of the moon was first photographed by Luna 3 in 1959. The above is a recent image captured by NASA’s LRO.
If you are asking why we can only see the near side from Earth, that’s because the moon tidally locked. It used to spin faster than it orbits, but just as its gravity causes a tidal bulge in Earth, our gravity causes a bulge in the moon.
Tidal bulges are carried along by the rotation of the body in question, and so create a slight gravitational imbalance. Today, this imbalance is pushing the moon away as a rate of 3.5 cm per year and slowing Earth’s rotation by about a millisecond per century. In the past, that same process slowed the moon’s rotation until it’s rotational and orbital periods became the same.
Now the moon’s stuck with it’s tidal bulge facing us. Any perturbation that would tend to turn the moon with respect to Earth gets cancelled out by the pull of our gravity on the moon’s bulge, and nothing is ever likely to disturb it enough to break free.