Science

Astronomer creates stunning animations showing the true scale of our solar system

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We do not always realize how much we are dust particles in the vastness of the universe. Thus, every day we observe our sun, like a small sphere in the sky, without really realizing the real size of this star. And for good reason: we are separated by almost 150 million kilometers! However, one astronomer managed to put things into context: he has been creating amazing animations for several years, including one in which all objects in our solar system are represented to scale.

Japan Space Agency planetarian (and former NASA researcher) Dr. James O’Donoghue made a short video in 2020 showing all the planets around us to scale in terms of size, rotation rate and tilt. The result allows you to have a completely different point of view on the world, and the size of our planet seems really ridiculous next to the gas giants (especially compared to the Sun!). The video has already received over 15 million views on Twitter.

The smallest object in our solar system is the dwarf planet Ceres, which lies in the main asteroid belt. Thus, this object with a diameter of about 950 kilometers opposes Jupiter, the largest planet in our system, with a diameter of almost 140,000 kilometers (almost 11 times larger than that of the Earth). The relative sizes of each planet are fairly well known; on the other hand, it is interesting to be able to compare their rotation speeds here.

An exciting prospect

Note that relative distances are not explicitly taken into account here, so that all the planets can be represented on one screen. As the animation progresses, revealing more and more objects from our solar system, we see that the Earth is one of the fastest rotating planets; its rotation speed is very close to that of Mars. But we quickly realize that all the giant planets are superior in this respect!

While it takes the Earth a day to make a complete revolution, Neptune and Uranus rotate on their axis in 16 and 17 hours, respectively. But all records are broken by Jupiter, whose estimated rotation period is about 9 hours 55 minutes; not far from it is Saturn with a rotation period of about 10:30.

We also note in passing the very strong inclination of the planet Uranus with respect to the normal to the ecliptic: the inclination of its axis is approximately 97 °, therefore its poles are turned towards the Sun alternately – for comparison, the axis of our planet is inclined by about 23 °. According to experts, such a sharp tilt was likely caused by a collision with a young protoplanet.

At the end of the animation, the Sun clearly stands out in the background, with a diameter of almost 1.4 million kilometers! A huge star compared to our very small planet, just over 12,700 km in diameter … If the size of our star is already very impressive, then nevertheless they remain very modest compared to the largest stars in our galaxy. For example, the star Mu Cephei, also called the Garnet star, located in the constellation Cepheus, has a diameter of more than 1000 times that of the Sun (that’s equivalent to 1260 solar diameters exactly)!

Currently, the record for size is held by another red supergiant: UY Scuti, located in the constellation of the Shield of Sobieski. Its radius is approximately 1708 solar radii (almost 1.2 billion kilometers). We are definitely very small compared to these oversized objects…

Lots of videos to discover

Note that James O’Donoghue has already made many videos of our Solar System to scale. Earlier this year, he notably posted a video showing the sizes, rotation rates and inclinations – to scale – of the planets in our solar system (including Pluto and Ceres). He points out that the planets probably had the same tilt at the beginning, but collisions, tidal forces and/or planetary migration have more or less increased this tilt afterwards.

Previously, the scientist also made a video illustrating in real time the path of light from the Earth to the Moon, or, even more amazingly, the path of light in real time from the Sun to the Earth, passing through Mercury and Venus. Obviously the video is a little over eight minutes long, which is the time it takes sunlight to travel 149.6 million kilometers… A few weeks ago he posted an even more didactic video explaining the mechanics of the seasons, solstices and equinoxes:

While it is relatively easy to represent each planet on a scale, the main problem remains with the representation of distances. The specialist explains that he must reduce the size of the Sun, ignore relative distances, or reduce orbits in order to be able to display everything on one screen in his animations. “It’s hard to imagine the actual size of the solar system because space is basically… space,” he said in 2019 on his Twitter account. All of these videos are equally impressive.

YouTube/James O’Donoghue.

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