Ancient Egyptian Astronomy

The Ancient Egyptians cared a great deal about astronomy. Probably too much, in fact. According to their beliefs, the movements of the planets and stars played a role in the annual flooding of the Nile river, and if you are an Ancient Egyptian, you will do just about anything to appease the Nile, and that includes laboriously tabulating star positions for millennia.

Astronomically inspired stone circle at Nabta Playa from the fifth millennium BCE.

Beyond simply recording positions, the Ancient Egyptians also devised methods to be able to predict the behaviour of astronomical objects in the future, and even to use stars to tell the time of day. One of these time-keeping methods functioned through the use of a “star clock”. To use a star clock, one needed two people. One person to sit facing North, and another to sit facing them. As the night passed the recorder would mark when certain stars passed behind the body of the other. The information gathered from this could then be used to find an entry in a table which gave the correct time.

Astronomy even came to have a religious significance. The tombs of various pharaohs feature many artifacts and murals depicting the movements of the stars and charts representing their positions. It is theorized that knowledge of these stars would benefit the pharaohs in navigating the realm of the afterlife.

A star chart from an 18th dynasty tomb. The small, repeated figures on the borders that resemble stars represent stars.
Another star chart from the tomb of Ramses VI, featuring Nut, the Egyptian goddess of the sky, in the top left corner.


Hydrothermal Vents: The Origin of Life?

Astrobiology is becoming an increasingly discussed topic as new exoplanets are being found and we discover more about the worlds of our own solar system. Of course, for there to be life on other planets, it first needs to come into existence on its own through abiogenesis, or the creation of life through non-biological sources. Perhaps our best way to learn about how abiogenesis might occur on other worlds is to consider how it occurred on ours. While we can never be entirely sure as to the causes of life on Earth, one of the leading candidates for the catalyst behind abiogenesis is the humble hydrothermal vent.

A hydrothermal vent at the bottom of the Pacific Ocean, fumin’ away

Hydrothermal vents are the result of water underneath the seafloor being heated by the mantle and erupting out of the ground in sustained streams, sometimes at temperatures of over 300 degrees Celsius (although the water is still liquid due to the extreme pressures of the deep ocean). At the depths that they are found, no sunlight at all reaches the seabed, so you might think hydrothermal vents would be barren of life…

But you would be wrong. Behold, a hydrothermal vent colony of tubeworms

Hydrothermal vents actually have many times the biological density of the surrounding seafloor, primarily due to extremophile bacteria which get their energy by processing chemicals in the hydrothermal vent fluid. This is significant because these bacteria due not rely on the sun for energy, even indirectly (unlike most other deep-sea creatures, which feed on detritus further up in the water column). And because they are in the deep sea, they are shielded from events which occur further up, such as asteroid impacts or extreme solar radiation. This makes hydrothermal vents, which would have been much more common in Earth’s early life due to increased geological activity, ideal places for life to develop, providing a safe harbour from the outside chaos. Besides this, there are many chemicals present in hydrothermal vent fluid important for biological activity that were not present in the ancient atmosphere, such as methane and ammonia. Finally, the oldest known life that has been discovered are bacteria fossilized in hydrothermal vent chimneys, and this life appeared almost as soon as the Earth’s surface had cooler sufficiently to support an ocean.

Europa, a candidate for extraterrestrial life with possible hydrothermal vent activity

This all goes to show that other worlds, which have surface conditions very averse to life, may still be able to harbour it. Take Europa, whose surface is extremely cold and which has virtually no atmosphere. Any yet, it is known to be geologically active, with a subsurface ocean. So it is very possible that Europa is home to hydrothermal vents and if this is the case, it may present
the very same conditions that spawned life on Earth.

Probing the Mysteries of 50000 QUAOAR

Hundreds of millions of miles beyond the orbit of Neptune lurks one of the most intriguing objects in the Solar System, 50000 Quaoar.

The Mighty 50000 Quaoar

50000 Quaoar is notable for multiple reasons, but the most apparent is its name. Quaoar is the name of the creator deity of the Tongva people in the Los Angeles Basin. The deity Quaoar was believed to have control of a group of “avengers” who spied on humanity and enforced Quaoar’s will. While 50000 Quaoar certainly has an impressive namesake, the 50000 portion is also interesting from an astronomical point of view.

Ordinarily, Solar System objects will be named along with a number denoting how many similar objects had been found before. For instance, 1154 Astronomia was the 1154th minor planet found in the solar system. This chart has all of the minor planets found in order. But for a Solar System object as interesting as Quaoar, scientists decided to break entirely with this tradition to give it a number more fitting to its power; thus we have 50,000 Quaoar.

Another interesting fact concerning Quaoar is that it is a cubewano, and despite the fact that WordPress has underlined it in red on my screen, this strange term cubewano is really an English word. It comes from the provisional name of trans-Neptunian object 15760 Albion, 1992 QB1. 1992 QB1 was left unnamed for over two decades, so whenever another trans-Neptunian object was located it was named after this provisional name (if you say QB1 fast enough it begins to sound like cubewano).

Cubewanos are often very large. The largest of them Makemake is actually a dwarf planet, although this isn’t unique to Makemake. 50000 Quaoar may also be a dwarf planet, and it even has its own 50 km moon, Weywot.

50000 Quaoar looking menacing

Some scientists have hypothesized that 5000 Quaoar was originally much larger and collided with another trans-Neptunian object, possibly even Pluto. Quaoar has also been chosen as a target for a flyby in the 2030s, so get your tickets soon.

The Star-Crossed Fates of Phobos and Deimos

The planet Mars was named after Mars, who to the Romans was the God of War. Its two moons, Phobos and Deimos, carry the names of the Greek Gods of fear (from which we get phobia) and terror, respectively.

However, despite the naming scheme that seems to be inspired by Death Metal, Phobos and Deimos are not very intimidating. The look much less like something menacing and much more like two misshapen, cosmic potatoes of especially low quality.

But we really shouldn’t be making too much fun of Phobos and Deimos. After all, they are doomed. “How can a moon be doomed?” viewers at home may be wondering. Here is how:

The Death of Phobos

From what we have observed about Phobos, it appears to be formed of many segments of rock weakly held together by gravity, coated by a thin crust. This loose conglomeration of rock does not fare well when tidal forces are applied. And unfortunately for Phobos, it is being subjected quite strong tidal forces, as it is much closer to Mars than Deimos. Moreover, it is being pulled in closer to Mars at a rate of 2 meters every hundreds years. At this rate, scientists expect that Phobos will either collide directly with Mars, or break up into a fancy planetary ring.

Neither of these options are very appealing for Phobos.

The Rejection of Deimos

Deimos is suffering (or will be suffering, at any rate) from the opposite problem that is afflicting Phobos. Tidal acceleration is slowly but surely increasing Deimos’ orbit, and eventually Mars will lose gravitational hold on Deimos. Deimos will then be sent to drift about the Solar System indefinitely, or until it crashes into something. It is thought (though there is not a consensus) that Deimos and Phobos are asteroids that were captured by Mars at some point in the past, so perhaps it would be fitting for Deimos to rejoin its friends in the asteroid belt. Still, one can’t help but feel for Deimos’ impending loss of glory, falling from the status of moon to lowly space rock.

Venera, or the Soviets’ many attempts to reach Venus

Despite being the sister planet of Earth, Venus is far from hospitable. Very far. Its atmospheric pressure at the surface is 92 times that of Earth’s, has an average surface temperature of 863 degrees Fahrenheit, and at higher latitudes sulphuric acid rains onto the surface.

So what better force could there be to attempt to reach, land on, and take pictures of Venus than the Soviet Space Program?

As it turns out, a different force would probably have been preferable, because the Soviets did not have an easy time getting to Venus. For reference, here are the results for their first eight attempts:

  1. Failed to leave Earth
  2. Communications lost en route to Venus
  3. Failed to leave Earth
  4. Failed to leave Earth
  5. Third stage exploded
  6. Did not reach Venus
  7. Did not leave Earth
  8. Communications lost en route to Venus

And hey, going 0/8 isn’t so bad, but remember: they have not even managed to reach Venus by this point, so all of that blistering heat and acid rain has not even entered the equation yet.

When the spacecraft actually manage to make it to Venus, things do not go well. For starters, only one of them managed to last over two hours before overheating and becoming crushed by the atmosphere. One lasted a mere 23 minutes. Venera 11 managed to land on the surface, armed with a color camera, but due to a design flaw its lens cover become stuck and no pictures could be taken. The new-and-improved Venera 12 had the exact same issue.

The Photos

Eventually, however, the Venera landers did manage to take some photographs of the surface of Venus, both black-and-white and in color. Here are some of them:

From Venera 9 and 10
From Venera 13
Still from Venera 13

The Aftermath

What happened after the Soviets obtained these images? In fact, they realized that idea of landing on Venus was a little too ambitious, and the next four (and final) missions to Venus were flyby’s.

Since the last Venera landing in 1982, no spacecraft has landed on the surface of Venus. While there are some tenuous plans by the Russian space agency Roscosmos and the Indian Space Research Organization to launch orbiter spacecraft toward Venus in the late 2020s, there are currently no proposed Venus landers.

As such, it is likely that over half of a century will have passed, and our only knowledge of the surface of the planet closest to us will be a handful of dingy photographs taken by ill-fated landers, sent by a country that no longer exists.

MAGNETAR

Look out, it’s a magnetar

As you know, neutron stars are the result of massive stars (many times more massive the the sun) collapsing inward on themselves, leaving behind an extremely dense and energetic core. As you might expect these stars are extremely energetic — what you might not know is that sometimes as a result of the in-falling star materials angular momentum, neutron stars can spin. Sometimes they end up spinning very fast. These are magnetars. And as a result of their extremely rapid periods of rotation, they exhibit egregiously large magnetic fields. These fields are millions of times stronger than any man-made magnet. In fact, the magnetic field is so high around a magnetar that the field itself has an energy density 10,000 greater than that of lead, and distorts the orbit clouds of atoms into cylinders. I.e., you do not want to be close to a magnetar. Fortunately, they are so energetic that after around 10,000 years they effectively die, leaving behind a magnetized husk. Beware

Newton and Friends

Look at this man:

Isaac Newton

This is none other than Sir Isaac Newton (Dec. 25, 1642 – Mar. 20, 1726), who, among other things, laid the foundation for modern mathematics and physics. Of course, Wikipedia has more information than you could ever possibly want to know about this mathematician-physicist-philosopher-alchemist, but this site is shorter and is more focused on his scientific accomplishments.

You might be wondering what else was happening in the world while Isaac was attempting to turn lead into gold and calculating the orbit of Jupiter. Good thing you asked, because I’ve got two killer contemporaneous historical events for you:

Event 1: Qing Control of China

Flag of the Qing Empire

This flag, sporting a pretty rad dragon, represents the Qing, the last imperial dynasty of China. While the dynasty was established in 1636, it didn’t control China proper until 1644, which is, conveniently, two years of Newton was born. The Qing would continue to rule in China, in some capacity, until 1912 thus ending some 2,000 years of imperial rule in China.

Event 2: Coronation of Louis XIV

It’s Louis

This is Louis “the Sun King” XIV. He became king of France in 1643, which was after Newton was born. His ascension to the throne was kind of important because he was a fan of absolute monarchism, wherein the monarch holds absolute power and whose authority is granted by God. Mighty suspicious that he thought this, considering he was himself a monarch and all. Absolute monarchy in France was a contributing factor in the French revolution. Enough of Louis XIV and onto the main event.

Historical Person

Leo

You guessed it, it’s Leopold I, Holy Roman Emperor. He lived from June 9, 1640 until May 5, 1705, so he was around for most of Newton’s lifetime. Leopold did not like France. At all. In fact, he fought three separate wars with France, the last of which being the War of the Spanish Succession, where Leopold attempted to throw his son until the Spanish throne, getting to fight France as a nice bonus. Over one million people died in this war, and Leopold’s son didn’t even get the Spanish inheritance.

Conclusion

I think it is interesting seeing things completely unrelated to science which were going on at the same time as various scientific developments because these historical events are usually not mentioned when the history of science is being discussed. It was especially interesting seeing what was going in far away from these scientific events.


The OORT CLOUD and You

You might find yourself looking at a (to-scale) diagram of the planets of the solar system (and Pluto), such as the following:

A solar system model that suspiciously does not include earth…

and think to yourself “Wow, Pluto is so much farther out from the sun than the Earth is. The solar system is so massive!”. And while you would be correct in your statement, the orbits of the sun’s outer planets (and dwarf planets) pale in comparison to the true extent of our solar system. Enter: the OORT CLOUD.

Actually, the Oort Cloud is going to have to wait. First, we’re going to have to cover comets. For a comet to show its characteristic tail, it has to pass (relatively) close to the sun. This implies that its orbit must be highly elliptical so that it can be near the sun for a short period of time before moving far enough away that it reverts to its less aesthetic ball-of-ice-and-rock form.

Everyone knows about Halley’s comet, which becomes visible from Earth every 76 years. Combining this lengthy period with the above fact that comet orbits must be very elliptical, one can imagine that Halley’s comet is, at its furthest extent away from the sun, far away. An in fact it manages to reach a bit farther than the orbit of Neptune before crashing back toward the sun.

But, in the grand scheme of things, Halley’s comet actually has a fairly short period. The famous Hale-Bopp comet has a period of over 2500 years and, as you might guess, reaches much farther away from the sun than Halley’s comet: 183 AU, or roughly 6 times farther than Neptune’s Aphelion.

But wait, there’s more! This unassuming ball of rock:

is Sedna, a minor planet whose aphelion is 936 AU, or 30 times Neptune’s aphelion.

But even beyond Sedna, there is the Oort Cloud. The Oort Cloud is a theoretical cloud of gas and icy bodies which exists at the very edge of the Sun’s gravitational influence. This cloud is conjectured to exist at up to 200,000 AU away from the sun. In other words, the outer reaches of the Oort Cloud, should it exists according to these projected specifications, would be over six thousand times farther away from from the sun is than Neptune. This is the true extent of our solar system, beyond which point the sun’s gravity is no longer sufficient to pull bodies along with it as it wanders through the galaxy.

Comparison of the inner solar system versus the inner Oort Cloud.