How far can we stand from the Earth, can we see living dinosaurs?

The light reflected off Earth 65 million years ago is now 65 million light-years away, and an extraterrestrial civilization with a powerful telescope can see dinosaurs.

The answer is yes, in theory. The light reflected off Earth 65 million years ago is now 65 million light-years away, and an extraterrestrial civilization with a powerful telescope can see dinosaurs. In fact, such a powerful telescope will be unreasonably large.

Full answer: Light takes time to go from one point to another, so whenever you look, you are looking at the past. Suppose you stand 2 feet away from the computer screen, you are seeing these words for 2 nanoseconds ago. If you look at the moon, you are seeing the moon of a second ago. With the sun, the time interval is nearly 8 minutes. If, for some crazy reason, the sun disappears, we won't know it for the first 8 minutes after that happens.

If we stand far enough away from Earth, can we see dinosaurs alive?

In theory, hidden in the rays of light leaving the Earth millions of years ago is the image of dinosaurs alive. Because dinosaurs became extinct 65 million years ago, the nearest aliens could observe dinosaurs, if he knew where the telescope had to be located about 65 million light years from Earth.

In fact, this is very unlikely because the Earth is very small and 65 million light years is a great distance. In other words, most visible stars are only about 1,000 light-years away. The galaxy is about 100,000 light-years across. Andromeda is 2.5 million light years away from Earth.At 65 million light-years away, alien astronomers may come from Virgo galaxy cluster.

So if aliens want to see dinosaurs, they will need a giant telescope . Astronomers have had a hard time observing planets in their Milky Way galaxy, let alone intergalactic planets. In fact, only two such planets are observed. A long, Andromeda, and another "inter-galactic" planet is only 2,000 light-years away - because it is entered into the Milky Way band in a intergalactic collision.

Imagine the sun constantly shooting small balls in every direction. The number in question is billions and billions of spheres. These particles are photons, light particles. Some will hit a T-Rex and bounce, and fly into your eyes, then your brain will record it. The farther you stand from the T-Rex, the less of these spheres reach your eyes, the harder it will be for you to see the dinosaur. Some berries bounce off the ground and shoot at the universe. Telescopes work by navigating these spheres onto a wide plane and then focusing on a collection point, like a huge eye. Again, to do this we need an extremely large telescope.

If aliens want to see dinosaurs, they will need a giant telescope.

But don't let the actual conditions ruin the good problem, anyway, we also assume that the aliens are real. So how big is their telescope? Astronomy is very problematic, because the more you want to look away, the bigger the telescope you need to get the same resolution. If aliens want to make a very big glass to watch dinosaurs, we can use the lens resolution calculator to find the right size:

Angle ratio = 1.22 x Wavelength / Lens diameter

Replace the number: we will use a wavelength of 500 nanometers because it is the wavelength of the middle spectrum right between the green and blue, with a distance of 65 million light years. The ratio of the Earth's angle is equal to the radius of the earth divided by the distance.

Calculating the lens diameter must be about 5.8x1010 meters long, about 1/3 of the distance from the Earth to the sun. This lens will fill half of Mercury's orbit, and it only allows you to see the Earth as a pixel. This glasses must be very big.

But aliens want to see dinosaurs, not just Earth. If you want to see dinosaurs and not just a dot, you have to use the formula above but replace the Earth radius with the size of a dinosaur.

A Triceratops about 9 meters tall, T-rex about 13 meters, we'll use number 10 to calculate for rounds. This lens should have a diameter of 4.4 light years. Astronomers put funny names on telescopes, like "Very Large Array (Very Large Array)" or "The big telescope (The Overwhemingly Large Telescope)", but perhaps like that's not enough.

Anyway, there is a big problem that if you put too much weight into the same point, the surrounding space will deform, and gradually it will collapse into the center and create a black hole. For an object with a material density of glass, about 2.5 grams / cc, this process will happen very quickly. In fact, a glass sphere with a radius of 14 minutes of light has enough material density to create a black hole.

This is unfortunate at all !!!