Why does something look big? Is it because it actually IS big, or is it because it is close to us?
The closest celestial body to the Earth is our Moon. It’s an object that’s very easy to see without any visual aid, visible even in the daytime if you are observant enough. The Sun appears to be the same size as the Moon in our sky, but this is only because the much larger Sun is much farther away. Their actual sizes are much different.
What are the actual relative sizes of the Sun, its eight planets, and our Moon?
https://i.redd.it/yllhtptmu5z11.jpg
Clearly, the moon is not the largest object shown here; in fact, it is the smallest! The largest planet Jupiter is much larger, but even at its closest approach to Earth, it is more than 1500 times more distant than the Moon. At their closest approach, this is how large each of these solar system objects appear from Earth.
https://preview.redd.it/sb7t7mtjvx831.jpg?auto=webp&s=f299854dbb0126c08f5add60c0284c44431e0596
The only planet with a surface visible from Earth is Mars. Mercury is too small, too distant, and too close to the Sun. Venus is shrouded with clouds. The other planets have no solid surfaces. But Mars is closest to Earth, and therefore appears largest, at opposition, when it lies along a straight line connecting the Sun, Earth, and Mars.
https://svs.gsfc.nasa.gov/vis/a000000/a004400/a004465/print-still_mars_opposition.1917.jpg
This happens every 26 months, and next occurs on January 16, 2025.
But because Mars has an orbit that is highly elliptical, not circular, its distance from the Sun and therefore from the Earth varies a good bit. At its closest approach to the Sun, called perihelion, it is 128 million miles away; at its most distant, aphelion, 155 million miles. This opposition unfortunately occurs closer to aphelion than perihelion, and that will be the case well into the 2030s.
http://www.astras-stargate.com/images/mars/oppcycle.png
Still, if you can get to a telescope in mid-January under clear skies, you should still be able to see the largest dark surface markings, and the bright white polar ice caps should also be visible.
And give a thought while you’re looking to all the human-made hardware that orbits the planet, some inert and some still working, and the landers and rovers—and one helicopter—that rest on and still explore its dusty red surface.