The Hadean eon is the earliest geographic eon to exist (unless you count the unofficial Chaotian). It is the time from 4600 million years ago, when the Earth formed, to 4000 million years ago. The name is taken from Hades, god of the underworld in Greek mythology, and probably a fitting choice considering the hellish conditions that existed on Earth at the time. Although we are generally sure that will have been hot, perhaps up to 250°C, and that the atmospheric pressure may have been up to 30 times its current level, the exact atmospheric conditions are still mostly unknown. This mostly because there are very few rocks that even date back this far and so our avenues of study are limited.
Seismological waves are waves that occur underground. Earthquakes are the most observable result of seismological waves although these waves can be found permeating the Earth and not just at the surface. It is possible to examine the velocities of shear waves (S-waves) as they travel through the various layers of the Earth with the changing densities responsible for the changing speed of the wave. When a full map of the Earth’s mantle was performed plotting the speed of the waves through it two locations stood out as extraordinary. These are called the large low-shear-velocity provinces (LLSVP) and they exist in the lowest section of the mantle beneath the Pacific and Africa. They are 3000 km across (a large proportion of the Earth at that radius) and are believed to extend 1000 km up from the core-mantle boundary making up 3% of the Earth by volume. They are areas of the mantle where the speed of the transverse waves going through them drops by about 1% (it doesn’t seem like much but since most seismic waves go at about 13 km/s at this depth its pretty noticeable).
The US embassy in Beijing has many important diplomatic goals and purposes which help decide the future of arguably the two most powerful countries on Earth. One of its less serious activities, that it does when there is nothing else going on, is to give regular reports on the current level of pollution in Beijing which You can actually find on twitter @BeijingAir. On the 18th of November 2010 the air quality index report for that day was described as “crazy bad” as it was the first ever report of over 500 on the scale. This has occurred twice more since then. The air pollution in China is so bad that you don’t actually need to go to China to find it as the smog has been shown to reach all the way to California.
Sea spray is almost certainly a phenomenon that the reader will have heard of before. Despite it being one of the most common effects to occur on the boundary between sea and air the effect of sea spray on storms and hurricanes that develop over the ocean is still very uncertain. Some of the estimates performed on the number and sizes of droplets thrown into the atmosphere from the sea have massive error margins on either side of the predicted value. The difficulty in performing experiments, in the field, in extreme wind means that even the process of the spray forming itself is poorly understood.
Although fossilised remains of long dead animals are normally impressive (in size at least, as small fossils are much more likely to shatter under natural stress) what is really amazing is to find preservation of an animal’s soft tissue. Fossils are really just rocks that have taken on the shape of the bone as if poured into a mould, any soft tissue that can be recovered is the actual flesh that existed on the animal.
The Santana Formation in Brazil is a place of sedimentary deposit formed in the early Cretaceous period. The remains found here are located in deposits called Konservat-Lagerstätten which developed in an anoxic environment so the potential for rotting is minimised. This region is particularly known for its fish of which some 25 species have been found with the contents of their stomachs preserved. Once, the entire heart and connected valves of one of these fish was recovered, an incredibly rare find indeed.
I have written a post before about the initiation and development of lightning in clouds. This previous piece of writing focuses on the photographic evidence provided as a way of analysing lightning production while this current study focuses more on looking at accompanying events to lightning storms to see if current theories hold up. To this day we still do not know what physical mechanism lies behind lightning production in thunderclouds and we also don’t know why different types of lightning leaders (channels of ionised air which lightning will follow) are created and then propagate. Considering that lightning is not a very rare natural occurrence its creation has been described as “probably one of the biggest mysteries in the atmospheric sciences.”
Our star is quite unique even if its size and colour are not taken into account. This is because the more we search the universe the more we realise that stars are more likely to form in binary pairs rather than on their own, a fact explained normally through the conservation of angular momentum. There were even suggestions that our Sun may have a partner that comes by in a wide orbit every so often, although this seems questionable at best. Of course, the high population of binary stars means, somewhere in the universe, there’s going to be a planet at least somewhat similar to Earth in one of these systems.