Right here on earth there are really tall mountains. Mount Everest is the highest peak and then there’s Mauna Kea in Hawaii which is supposed to be the tallest. Yes, even taller than the Mt. Everest. To add to it, there’s one highest unclimbed mountain – Gangkhar Puensum – in Bhutan.
If we zoom out a little and put the whole solar system in our radar, things change. Mt Everest or even Mauna Kea are no where near the tallest mountains we have in our solar system. For instance, Olympus Mons, a shield volcano has, for a long time, been considered the highest peak in our solar system.
This is how it compares with mount Everest, for example. The peak of Mount Everest measures 8,848 meters. It’s absolutely huge. And yet, Olympus Mons on Mars is about 2.5 times higher! It measures about 22 kilometres in height. This image clearly shows how it compares with our tallest and highest mountains…
And yet again, even Olympus Mons, which has had the title of the tallest mountain in our solar system for several years, is believed to be no longer the tallest one.
A recently discovered peak in a proto-planet called Vesta is probably now the tallest mountain in our solar system. However, since this one – Mount Rheasilvia – is estimated to be only a few 100 meters taller than Olympus Mons, it has not very clearly dethroned Olympus Mons. Still, the data is pretty solid and can be trusted.
Rheasilvia was a peak known to researchers since 1997. But it was in 2011, when the Dawn spacecraft passed it, the data became really clear.
A couple of months back I wrote about a miniature sealed self-sustaining ecosystem that an old man has been running successfully for more than 53 years now. The whole ecosystem surviving out of itself in a completely closed system for such a long time is really fascinating. It’s like a little planet.
What if I tell you, there’s a much larger version of this completely sealed biosphere in Arizona. Much larger than the bottle, but way too smaller than our planet, and yet it works like a little planet inside a planet.
They call it the Biosphere 2 (Biosphere 1 is the plane earth’s biosphere). It is a completely closed 3-acre facility, currently owned by the University of Arizona, which doesn’t allow any matter to go in or out. There’s just energy moving in and out of this little planet that is the size of 3 football fields. Exactly like a miniature version of our pale blue dot.
Think about it this way. If you had to make a pizza in a place like that, it could take you two months or more, assuming you had everything needed to make a pizza (goats/cows for the cheese etc…). Just thinking about it makes you appreciate the fact that we’ve come so far. So far, that we’re able to get a pizza right on our door step in under 30 minutes.
The Biosphere 2 was designed to get a deeper understanding on how the earth’s biosphere actually works. Also, its aim was to try and create a prototype space base for Mars – Something like a little planet earth where we could live in and could carry it with us on a trip to other planets.
In the Biosphere 2 are areas that are meant for humans to live. Besides that there is a miniature rainforest, a savannah, a desert, a marsh, and a little mini-ocean in there!
Jane Poynter, with her team, walked into this biosphere when she was 29 years old. She lived in there for about 2 years and then came out. The world felt like a completely different place to her. It is really interesting to hear her talk in this TEDx talk…
The sun – as seen from Earth
For most of us living on Earth (closer to the equator), the sun has followed a simple path throughout the years. It rises, goes up at noon and then sets for rest of the day. It is a simple straight line for the complete year.
For people living a little away from the equator, things get a bit interesting. There, the summer sun at noon is overhead, but the winter sun is low at noon, not overhead. It isn’t very easy for a person living near the equator to grasp this phenomenon well. You’ll have to go there and see for yourself. Or simply, the simulator at the end of this paragraph will help you understand it better.
At poles, the sun almost moves horizontally for many days. It keeps on making a horizontal circle around you. There, it is day for 6 months and night for the next 6 months. [Here is a sun path simulator for Earth]
However, nowhere on earth, things get as interesting as they get in the skies of Mercury.
The sun – as seen from Mercury
On Mercury, the sun appears to briefly reverse its usual east to west motion once every Mercurian year. The effect is visible from any place on Mercury, but there are certain places on its surface, where an observer would be able to see the Sun rise about halfway, reverse and set, and then rise again, all within the same day. It is indeed an unusual performance which isn’t easy for us Earthlings to digest. [See animation in the next paragraph]
Why does it happen?
Let us consider a simpler analogy – some planets (like Mars), as seen from earth, take a similar path. [see the animation for Mars’s path as seen from earth]
The planets, including Earth, all travel around the Sun in a continuous orbit. We can see them make their way across the sky in a straight line usually. However, every now and then a planet appears to turn around. After turning around, it appears to move back the way it came. This is called a retrograde orbit and is caused due to the difference in speeds at which the planets circle the Sun.
So, as we see Mars do a reverse from earth, a similar motion of sun is observed from the surface of Mercury.
[Apparent Retrograde Motion