This is a six minute long video that explains what scientists have been able to deduce by examining the Ultra Deep Field image produced by the Hubble Telescope.
I made a perhaps unusual interpretation of your question, by assuming you’re meaning to ask How would Earth look if we were living on a different planet of our solar system? (I changed my answer by assuming you meant “how would Earth look” rather than “how would we look”.) I will consider the question without the interpreted change at the end.
When you look up at the sky sometimes you can see Venus, our closest neighbor, and a planet almost the same size as Earth. To the naked eye it’s a very bright point of light in either the early morning or early evening sky.
If you were living on Mars and looked in the right direction at the right time of night and year, you would see Earth looking similar to what Venus looks to us now.
Through a large non-terrestrial telescope you could see Earth from anywhere in the solar system as long as it wasn’t behind the sun. It’s brightness would depend on what percentage of Earth was lit with sunlight relative to the observer in space, and how close to you Earth is as both you and Earth go around the sun at different speeds.
Now, let’s revisit the original question, “How would we look if we were living on a different planet of our solar system? “ and take the “how would we look” as is, without interpretation.
That brings up a whole other topic, like would we change over time if we were living on other planets so that we didn’t look exactly like humans on Earth look like now.
But I don’t want to get into that, as interesting a topic it could be, because I don’t think that’s what you were asking
by Wayne Boyd
Many others could answer this question better than what I can say. I’d only point out the person asking the question has it backwards in his/her question.
Agreed, in the mind of the public we’re all getting ready to go to Mars. But that’s not what’s really happening. NASA is gearing up to go back to the Moon, not Mars, just the opposite of what the person is asking.
Now I know we hear Elon Musk talking about starting some kind of permanent encampment on Mars, and I know he has plans to go there himself. Elon Musk’s company SpaceX is a NASA contractor, but that doesn’t mean NASA isn’t focused more on the Moon than Mars.
NASA’s idea is to establish a working settlement on the Moon, kind of like having astronauts living on the International Space Station now.
By Wayne Boyd
Here the question said “planet” and not “exoplanet” and therefore I’m going to answer this in regard to our own solar system.
You could debate this answer in various ways, but I’m assuming here that we’re only talking about the 4 rocky planets, Mercury, Venus, Earth and Mars, since the gas giants really don’t have a solid surface. The gas giants are Jupiter, Saturn, Uranus and Neptune.
I’m going to say, then, out of the planets that have a solid surface, Venus has both the most surface area (even though Earth is bigger than Venus) and Venus also has the most destructive surface in our solar system. Some might say Mercury has the most destructive surface. We’ll compare that option later on.
I’m also assuming we are talking about solid surface. Earth has a lot of surface water. Since we didn’t count the gas giants because there’s no solid surface, I’m not counting the oceans, lakes and rivers because they are not solid surfaces either.
29% of Earth’s surface is solid land and 79% is covered with water. We need to calculate how much land that is, and to do that we’ll use square kilometers (km2). Most estimates
put it just over 148 million km2. A couple put it just over 150 million km2.
Let’s just round it out at 149,000,000 km2. That’s 149 million square kilometers.
Surprisingly, Mars, which is much smaller than Earth but has no surface water, has a similar surface area to Earth. Mars has 144.8 million km2, almost as much as Earth. So Mars is competitive with Earth in land area. It’s also got a destructive surface because the atmosphere is very thin and has almost no oxygen. It’s poisonous to breath the atmosphere on Mars, but it’s not the most destructive of the four.
Of the four rocky planets, Mercury has the least surface area, which brings us back to Venus. Venus has no oceans, like Mars, and it’s bigger than Mars. Earth is the biggest of the rocky planets in our solar system. Venus is slightly smaller than Earth, but since there’s no oceans Venus has more solid land area. Venus clocks in with a whopping 460.2 million km2 of solid land. So Venus wins with the most solid surface area.
Now, I voted Venus as having the most destructive surface as well, but it’s a toss up with Mercury. The atmosphere on Venus is really harsh and it’s thick so the atmospheric pressure is equivalent to that of 3,000 feet underwater on Earth. It’s also 872 F (467 C), hot enough to melt metal, and it rains sulfuric acid. Again, we’re not talking about the gas giants because they don’t have a solid surface.
Mercury, on the other hand, has almost no atmosphere, but it’s close to the sun and the daytime temperature is 800 F, hotter than Venus. Night time temperatures are minus 290 F. But it doesn’t rain sulfuric acid like it does on Venus!
So I vote for Venus as the planet with the most solid surface area and the most destructive surface in the solar system. It’s still up to debate. Earth’s globe is bigger than Venus, but then again, if we don’t count the gas giants because they have no surface per se, then I figure we can’t count the oceans on our planet because they are liquid, so Venus wins in both categories.
The Russians have sent several probes to the surface of Venus. Here’s what it looks like.
By Wayne Boyd
Air pressure works like water pressure. The deeper you go in water, the more the pressure because of the weight of the water above. Similarly, the lower you go in the atmosphere the more the pressure. At sea level, air pressure is normally about 14.7 pounds per square inch. This can be measured with an altimeter, which is used on aircraft.
Mount Everest is so high that climbers usually need to carry oxygen to go the summit. Commercial airlines go even higher.
When you get about 62 miles up (100 km) you’re at air pressure that is basically zero and you are above most of the atmosphere altogether.
The International Space Station orbits around 250 miles up, but there is still some, very thin atmosphere up there that eventually slows down the ISS, requiring it to be boosted once in awhile.
Eventually you come to deep space, and there are some molecules floating around out there, just not very many. So space isn’t completely empty, just mostly empty. Sometimes there are molecular clouds in space in regions where stars are forming, and the molecules floating around are a little denser.
If you went outside on a spacewalk on your way to Mars, took an empty bottle with you and opened it and then sealed it, once inside the spaceship you’d find your bottle had nothing but a vacuum in it. The free floating molecules out there are so sparse you’d not find any inside your little bottle.
By Wayne Boyd
The human race will be much changed. The reason the golden record was included on the Voyager spacecrafts was twofold. The main reason was a mechanism to inspire public interest (and therefore funding) for the project, which was to explore the outer planets in our solar system and interstellar space. The other reason was that Voyager I was going to pass within 1.6 light years of the star called Gliese 445 in about 40,000 years. In case any intelligent space traveling beings over there might notice Voyager I drift by their star 1.6 light years away, they might go out, retrieve it, and discover the Golden Record.
To compare that to us, if an alien spacecraft the size of Voyager I passed by within 1.6 years of our own sun we would not be able to detect it. It’s too small, and out many times farther than the Voyagers are now from Earth. It would be many times outside the solar system entirely.
Now, let’s assume that 40,000 years from now Voyager I is drifting by within 1.6 light years of Gliese 445 which is 17.1 light years away from us and alien astronomers on a planet over there did somehow notice it. Let’s say their alien scientists then launched a probe to investigate and find the Golden Record. What would happen? That’s the essence of your question, right? Well, let’s look at it.
To send a probe from an alien world to Voyager I as it passes by the star Gliese 445 their probe would have to travel 1.6 light years, which would take thousands of years. But once reaching Voyager I, the probe could communicate back to their alien world in only 1.6 years, with a 3.2 year return signal. So let’s say they did it.
The Golden Record is designed to indicate to an advanced alien civilization that other intelligent beings are “out there.” This would be extremely exciting for them to realize someone else (Earth) is out there. They might try to send a radio signal in our direction to let us know the message was received. The message would take 17.1 years to reach Earth, so basically, 45,000 years from now the message from the aliens might reach Earth, but would anyone still be around to listen? My estimate of time is the 40,000 years for Voyager I to reach that far, another 4,000 years or so for their space probe to reach Voyager, and a few years communicating with the probe to figure out what it found. Nothing here is true math. It’s just very round, hypothetical numbers.
Once the aliens realized there was another planet with intelligent beings on it, they might try to communicate with us even though we are more than 17 light years from them.
So a form of communication could eventually be established. Considering the speed of light with a return message taking 34 or 35 years (the time in light years and back) it would be a slow, gradual communication. Interstellar travel between the two civilizations would not be feasible, however. It would take the spacecraft about the same time as it took Voyager, or maybe they could half the time with some kind of alien propulsion system. UFO conspiracies aside, travel over those distances isn’t realistic.
The best could be communication.
Then again, the human race will probably be much changed 45,000 years from now and who knows if anyone will be listening by then, or conversely, if there is an alien civilization orbiting on a planet around Gliese 445 now, will they still be around by the time Voyager I reaches there?
Some people on Earth would not believe it or even care. Scientists, if there are any scientists left 45,000 years from now would be excited. I’d imagine it would be about the same for the aliens, but who knows what kind of organization they might have over there.
Basically, it would be largely ignored by the public.
By Wayne Boyd
Actually, this is an interesting question and I think I can provide an interesting answer.
To know what the people of the world want aliens to know about us, look no further than the Voyager spacecrafts. When we launched them in 1977 they were on a mission to explore the planets in our solar system, but afterward it was known they would be flung out of our solar system to drift in interstellar space for tens of thousands of years, and interstellar space is where they are both now.
So physicist Carl Sagan had an idea to place a golden record on each spacecraft with a message from Earth to any aliens who might come across them in the eons to come. According to Wikipedia, “The records contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form who may find them. The records are a sort of time capsule.”
So what’s exactly on this record, and what did mankind in 1977 want future aliens in space to know about us? The contents of the record were decided by a committee from Cornell University and headed by Carl Sagan. It took more than a year to decide on the contents, and contains 115 images of Earth and natural sounds of the planet like wind, surf, thunder and whales.
There’s images of DNA and music by Mozart and Beethoven and a whole bunch of other stuff to indicate we are an intellectually and culturally developed civilization of beings.
Yes, I believe in space aliens, and unlike others, no, I don’t believe they are “here” nor do I ever think they will ever be able to come here, nor us go there.
Space is so big, that given we’ve been emitting radio waves for over a hundred years, the radio “sphere” in space coming from us hardly encompasses very many stars at all. We live in a huge galaxy, one of billions of galaxies, and in our little corner of our galaxy our radio waves, traveling at the speed of light, haven’t even reached a significant portion of our own galaxy.
In the image below, you can see just how tiny an area that is, represented by the small blue circle, or dot.
That being the case, unless there are aliens that want to visit us and “hide among us” (for whatever reason), they’d really have to come from somewhere pretty close.
I don’t see it.
Regarding “UFOs,” aka unidentified objects in the sky, there are many natural phenomena that we don’t yet understand, but to take it there is something we have yet to identify and then extrapolate that it is some kind of alien spacecraft visiting across thousands of light years just to come here, is more than a stretch. It’s not science.
Data and graph from the New York Times 10/24/2020
This is the kind of question, “How do we get to Mars?” that normally would take a lot of discussion and involve a whole lot of mathematics.
I’m going to try to explain it simply and to the best of my limited ability.
Mars is in orbit around the sun. Earth is in orbit around the sun. Earth, being closer to the sun, orbits faster. Mars orbits more slowly. So you have to wait until the two planets are lined up to launch, which happens about every 2 years or so. But it’s not a straight shot out to Mars. Everything works following the rules of orbital mechanics.
Essentially, we launch a spacecraft from Earth into a highly elliptical orbit around Earth. This orbit is so elliptical, that it extends all the way out to the orbit of Mars. You time it so just as this spacecraft reaches it’s farthest point from Earth before beginning it’s return journey, Mars comes along in it’s orbit. The spacecraft meets up with Mars.
The image above from the Jet Propulsion Laboratory website of NASA illustrates how this transfer of an elliptical orbit from Earth catches up to Mars. This process takes about 9 months for a spacecraft like this to reach Mars, and can be accomplished only about once every 2 years.