Science is one of the greatest achievements of humankind, and yet when our theories are confronted with reality, they often turn out to be coarse approximations. In astronomy in particular, this leads to a race between theory and observations, and often we discover things that seem to challenge everything we know.
As a case in point, here are some excellent examples of phenomena that really make researchers scratch their heads.
Horizon Problem
The Big Bang theory is one of the most successful theories of the 20th century. It is supported by plenty of observational evidence, and yet there are still a few kinks to iron out. One is called the "horizon problem", which tells us that the universe is too uniform. It’s the same everywhere.
If we look at two opposite points of the universe (so we can see them, but they can't see each other), we see that – using the temperature map of the universe known as the cosmic microwave background – every region is weirdly the same temperature. So how could they all be at the same temperature if these regions never touched? According to thermodynamics, this means at some point they should have been in contact.
An explanation for this is that they did touch. The universe must have been a lot more closely packed than we originally thought. If this is the case, then we need a mechanism to make the expansion happen faster at the very beginning. Otherwise, we just can't explain the current size. The solution for all these problems is called "cosmic inflation", but we are yet to confirm that it truly happened.
Tabby’s Star
KIC 8462852, or Tabby’s star, has been described as the most mysterious star in the galaxy – and for good reason. Its light variation is absolutely unpredictable and is like nothing we have ever seen before. Over 1,600 days of observations, the amount of starlight appeared to dip by up to 20 percent on several occasions and at random intervals. This is not easily explained by a standard orbiting planet or that it is a variable star. There are also indications that the star might be experiencing a constant dimming, which is weird to say the least.
Explanations range from serious ones, like a ringed planet or comets blocking the light, to more facetious ones like a megastructure surrounding it. While both the comets and megastructure ideas have been discarded, we still haven't uncovered the cause of this flickering.
The Star That Died Twice
In 2014, astronomers witnessed a star going supernova. This is already an unusual event, but what makes it truly special is the fact that the star already went supernova in 1954. So far, the best explanation for this event is that it's a pulsational-pair instability supernova, in which a truly massive star in effect blows off its outer layer, leaving its innards intact to start the process over. The only problem with this hypothesis is that, according to our theories, the stars that explode this way shouldn’t exist anymore. But apparently, the cosmos doesn’t care for our theories.
Solar Corona
The Solar corona, the aura of plasma that surrounds the Sun, is too hot. It exceeds millions of degrees and we are not sure how it got that hot. It is about 1,000 times hotter than the Sun’s surface, which needless to say is a bit counterintuitive. After all, you wouldn't expect the air over a fire to be hotter than the fire itself. Unlike a fire though, the corona extends for thousands of kilometers and somehow is still much hotter than the surface below as well as the interplanetary space beyond.
Researchers are unclear what could cause the corona to be so hot. There might not even be a single process, with the high temperatures reached thanks to multiple factors. Several proposed mechanisms show promise (such as nanoflares), but there are still many questions left to answer.
Venus Winds Speed
Winds on Venus move too fast for our current climate models of how an atmosphere should behave. They move 60 times faster than the planet’s rotation on its axis and it's not easy to reconcile this with what we know. On Earth, winds are created by pressure differences in two nearby areas. These pressure differences are created by differences in temperature in the air. And yet Venus doesn't have any dramatic gradients to justify such powerful winds.
The clouds on Venus don't make sense, either. There is a huge stationary wave in the clouds of the upper atmosphere and irregular patterns on the planet’s night side, as well as a weird Y-shape visible on its day side. Observations of the changing weather are still being taken, so perhaps one day we will uncover the cause of such complexity.
Saturn’s Hexagon
If we are talking about clouds, we must mention Saturn’s polar vortex – a color-changing, hexagonal feature with an unclear origin. The hexagon was first observed in 1981 by Voyager, and then seen in better detail by Cassini.
We know that it changes from a blue hue to a golden color with the seasons, but physicists are still trying to understand how it formed. While researchers have been able to recreate hexagonal vortices in the lab, more needs to be done to fully understood it. For example, we don’t know why the southern pole of the ringed planet doesn’t have a similar system.
An Exoplanet Too Big For Its Star
NGTS-1b is a Jupiter-sized planet similar to the many hundreds that we have discovered in the last few decades. But unlike others, it orbits a red dwarf – a small star that is just about 12 percent of the Sun in volume.
Planets that big shouldn’t form around stars that small. According to the current view, dwarf stars can’t collect enough material to form big planets. And yet, somehow, one has. Researchers are now looking for more examples in order to better understand what’s going on.
1
