How big is our solar system? If we watch the sky on a clear night,
far away from the pollution of the cities, we immediately understand that the universe is huge.
It is just a sensation, perhaps based on naive and intuitive reasoning:
if we see a lot of stars, let's say, thousands,
maybe millions of stars...this means the universe is really, really big.
I mean, the planets themselves, are big. We know that the Earth itself, is big, and yet
it is a quite small planet, compared to gaseous balls like Jupiter or Saturn...
Despite that, though, it is still big for us, humans. Man, we are so small!
Then, if we take into consideration the distances
between planets or the distances between stars, well...those are hard to picture.
It's hard to have a feeling of how distant really the planets or the stars are.
Have you ever wondered how big our Solar
system is? This question might seem very simple to answer, but is it?
===================================================
Let's give the real numbers first.
Light would from the Sun takes about 555 days to reach the edge of the Solar System compared to
8.25 minutes to reach the Earth. It’s clear we’re talking about some IMMENSE distances which can be
hard to imagine. Broadly speaking, the diameter of the entire solar system is 100.000 times the
distance from the Sun to Earth. If you managed to design and build a spacecraft traveling at the
speed of light, it would basically take one year and a half to reach the end of the solar system.
Don't worry though, because it would be a very nice trip: you wouldn't get bored at all!
For instance, approaching Jupiter,
you would see that it would take 11 Earths to fit across its diameter.
However, we will probably never be able to travel at the speed of light,
so the trip might get boring. If we had to travel on a planet,
at normal speed, it would take us over 570 years to get to the dark, cold, and blue Neptune.
Of course, our patience would then be rewarded by this amazing view:
Only one spacecraft had the honor to visit this beautiful planet so far: Voyager 2.
Because of this, a majority of pictures we see of these two ice planets came from this
spacecraft. It was identical in form to its sister ship, Voyager 1. The probe is currently
moving away from the solar system and is heading out into interstellar space.
For example, Voyager 2 was launched on August 20, 1977, and in 2018 NASA announced it had incredibly
reached the Heliopause, the theoretical boundary where the Sun's solar wind is
stopped by the interstellar medium. Voyager 2's twin was Voyager 1,
and it is the most distant human-made object. This amazing spacecraft has been in space for
more than 40 years and it still has not escaped the influence of our Sun.
As of Feb. 1, 2020, Voyager 1 is about 13.8 billion miles (22.2
a billion kilometers) from the Sun — nearly four times the average distance from the Sun to icy
Pluto. That just goes to show how big our solar system really is.
The problem of distances was a huge one in astronomy. All over the years,
astronomers had been searching for a basic unit of measurement.
The first one they could come up with was the so-called Astronomical Unit,
which is defined as the distance between the Earth and the Sun. Measuring this distance,
however, is no picnic! It took a lot of studying, effort,
and clever minds to finally have a nice estimation of this distance.
The Ancient Greeks used naked-eye observations to estimate the distance
to the Sun in terms of Earth radii. From the 17th century through to the
19th century, observations of parallax – the apparent change of position of an
object against the background when viewed from two different positions – allowed increasingly
accurate measurements of planetary distances. More recently, extremely precise distances
have been obtained using radar and by calculating orbits from multiple images.
Nowadays, we know this distance accounts for 149 million kilometers (92,
58 million miles). It is almost a magical number, and if you
are an astronomer, or you're simply fond of astronomy, you HAVE to remember it by heart.
The astronomical unit is the starting point for all the distances measurements
in the solar system, and beyond! Once you know the distance from the Earth to Sun,
you can make some observations of planets and, using Kepler's third law, you can reconstruct the
distances of the planets. This gave astronomers the first idea of how big is our solar system.
They just needed an instrument – the telescope – and a nice law – Kepler's third law! It seems
an easy task now, but there's a lot of thinking and reasoning behind it.
Nowadays, we know that the distance to the furthest planet Neptune is
nearly 27 billion miles. You might want to compare
this to the distance the International Space Station travels in 24 hours (397677,563).
Hey, if you are still here, it means you are really enjoying
this video! Why don't you subscribe now and press the bell notification?
Now. Someone said: if you can't explain it simply, you don't understand it well enough.
So let's try to get a better feeling of the distances in play.
Let's say we wanted to draw the solar system to scale, using some conventional walkable units.
These are the distances of the planets in terms of Astronomical units.
Mercury 0.4 AU Venus 0.7 AU
Earth 1 AU Mars 1.5 AU
Jupiter 5.2 AU Saturn 9.6 AU
Uranus 19.2 AU Neptune 30 AU
To make you walk the solar system, we will need to convert the Astronomical
Units to something walkable. We can accomplish this task by multiplying
the number of astronomical units by 100 and using centimeters as a unit of measurement.
Doing this, we could start with the Sun at 0 cm, and then draw Mercury at 40 cm, and Venus at 70.
The Earth would be one meter away from the Sun, and to reach Neptune,
you would need to walk a distance of 30 meters.
In this way, Usain Bolt could run the Solar System in less than 3 seconds! Congrats!
================================================
But what if we wanted to see things from the perspective of light?
How long would it take for a beam of really nice
and cute photons to travel the distances between the planets?
Photons released from the Sun reach Mercury after 3 minutes,
Venus after 6 minutes, and the Earth after 8 minutes. They are so fast, aren't they?
But as we go further from the sun, distances between planets stretch.
It would take 13 minutes to reach Mars, and 23 minutes to reach the dwarf planet Ceres.
Then, you will need to almost double this number to be able to reach Jupiter: 43 minutes!
In the end, our photons will cross Neptune's orbit in 4 hours and 10 minutes.
But the solar system doesn't end with Neptune.
After 5.5 hours they would reach the Kuiper Belt, and around 12 hours into their adventure, they
would begin to escape from the heliosphere into interstellar space. However, crossing beyond the
Oort Cloud may take them up to a year and a half. ===========================================
I think it's quite clear that, given the newest technologies,
we will never be able to reach the end of the solar system in a single generation.
Some scientists also believe that you could travel halfway to Proxima Centauri before you truly
leave the Sun’s sphere of influence (meaning that you would have to essentially travel to the next
star in order to leave our solar system).
Proxima Centauri is the closest star to us, and our family of photons would
get there after 4.24 years because it lies 4.24 light years away from us.
This means that the Sun’s influence extends at least 2.12 light years from Earth – or nearly
13 trillion miles. That’s just amazingly huge.
It's better not to think about it, or you will definitely feel very, very small. I
If we ever want to cross our solar system it would take us a staggering
30,000 years just to leave the influence of our sun, using our current technology.
That is just a very large amount of time for
a human being and a very boring journey too! ==============================================
Anyway, needless to say, we have some time to improve our technology,
and there's no particular need for us to leave the solar system. However,
we are trying to get to Mars. Probably within the next decade or so, we will see the first
black person and woman safely landing on the moon, as well as the first man walking on Mars.
It would be an amazing show for us on earth, and a huge leap for mankind, again!
Mars is the fourth planet from the sun and with our current technologies, it takes seven to nine
months to reach Mars, if you start the trip in the most favorable initial configuration.
This is something doable, and we can't wait to see more.
But what if we used the fastest spacecraft ever built, the parker
solar probe, to get to the Red Planet? Parker Solar Probe reached a top speed of
101 miles (163 kilometers) per second during its 10th close flyby of our star, which
translates to an eye-watering 364,621 mph (586,000 kph). According to a NASA statement,
when the Parker Solar Probe comes within 4 million miles (6.2 million kilometers) of the solar
surface in December 2024, the spacecraft's speed will top 430,000 miles per hour!
If the Parker Solar Probe managed to achieve the speeds reached during its
10th close flyby of the Sun and took a detour from its sun-focused mission to travel in a
straight line from Earth to the Red Planet, the time it would take to get to Mars would be:
Closest possible approach: 93 hours Closest recorded approach: 95 hours
Farthest approach: 686 hours (28.5 days) On average: 384 hours (16 days)
Of course, the problem with the previous calculations is that they measure the
distance between the two planets as a straight line, but engineers know
paths and orbits in the universe are always curves because gravity bends the spacetime.
Moreover, these calculations assume the planets don't move with respect
to each other for the whole trip. But this is not true. In reality,
the planets are continuously moving in their orbits around the sun!
That's the reason why engineers must be able to calculate the ideal orbits for sending a
spacecraft from Earth to another planet. So, broadly speaking, how long it takes to
reach Mars – or any other planet - depends on where in their orbits the two planets lie
when a mission is launched. It also depends on the technological developments of propulsion systems.
For example, a promising propulsion system is photon propulsion.
Photonic propulsion works by firing lasers at a reflective material like a solar sail.
Though the photons in the laser do not have mass, they do have energy and momentum,
and they transfer a small amount of kinetic energy to the reflective surface when they bounce off.
In the frictionless vacuum of space, the continued acceleration could hypothetically
push a spacecraft to around 30 percent of the speed of light, the types of speeds we
have achieved in partial accelerators. It will likely be decades before photonic propulsion
could actually be used for space travel, but the fact that the technology seems to work is
exciting enough to start paying attention to it. This video ends here! What do you think about it?
Let us know in the comment below! And if you enjoyed the video,
don't forget to share it, and I'll see you next time on the channel