The Comet Time Forgot… Until Now

A stone carving at a major archaeological site suggests a comet struck Earth thousands of years ago and started an ice age.

Göbekli Tepe is an archaeological site located in modern-day Turkey.  Built before Stonehenge, it served as an ancient temple site and religious center where multiple people would gather, but it also seemed to have been an astronomy observatory.   Archaeologists have studied several stone carvings at Göbekli Tepe.  The Vulture Stone, however, depicts a major astronomical event that changed human history.

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Replica of the Vulture Stone at Göbekli Tepe

The Vulture Stone depicts an ancient comet impact.  Archaeologists found the vultures and animals featured on the pillar correspond with ancient constellations and the comet.  They traced the positions of the constellations to around 10,950 BC, nearly 13,000 years ago.  This is also the date when a mini ice age called the Younger Dryas began.  The comet impact could have caused this ice age.

What happened was that the comet’s nucleus broke apart and struck the Earth.  The carving of a man with a missing head might indicate a significant loss of human life.  The ice age that followed led to the rise of agriculture.  The barley, wheat, and animals that hunter-gatherers relied on were in short supply during the Younger Dryas.  Humans had to resort to settling down, growing their own vegetables and fruits, and raising livestock.  The Younger Dryas herald a new age in human development, one where agriculture led to rise of villages, cities, and civilizations.  And it all could be attributed to this one comet impact.

 

Sources: Ancient stone carvings confirm how comet struck Earth in 10,950BC, sparking the rise of civilisations

Ancient Stone Carvings Show a Comet Swarm Hitting Earth Around 10,950 BCE

 

 

 

An Exoplanet Near You

Last year, in August 2016, astronomers discovered an exoplanet within Alpha Centauri, the closest star system to our Sun.  Only 4.3 light-years away, Alpha Centauri consists of the binary stars Alpha Centauri A and Alpha Centauri B, and the red dwarf star Proxima Centauri.  Orbiting in the habitable zone of this red dwarf is an exoplanet named Proxima Centauri-b.

 

Artist's impression of the planet orbiting Proxima Centauri
Artist’s impression of the surface of Proxima Centauri b

Proxima Centauri-b has a mass of 1.3 Earths and orbits its star at approximately one-tenth the distance of Mercury’s orbit around the Sun.  Despite being at such a close range, the planet remains relatively “habitable” due to Proxima Centauri being a red dwarf and weaker than our Sun.  In these conditions, the planet could have sustained liquid water like Earth.  However, new data contest whether or not the planet might actually barren.

New shot of Proxima Centauri, our nearest neighbour
Proxima Centauri, the red dwarf star, as seen by Hubble

The issue lies with Proxima Centauri, which is a red M star.  Before red M stars reach full maturity, they usually experience great amounts of contractions.  The stars are brighter in the younger ages and release far more X-ray and UV radiation than our Sun.  Also, red M stars produce powerful solar flares capable of stripping away the atmosphere of a planet with a weak magnetosphere.

On the one hand, when Proxima Centauri was young, the habitable zone was farther out, and the exoplanet would not be in the habitable range.  The bombardment of X-ray and UV radiation and solar flares and the final solar winds could have wreaked havoc on Proxima Centauri-b’s surface.  All of its surface water would have evaporated, turning the entire planet into a great desert.

On the other hand, if Proxima Centauri-b had a strong hydrogen-filled atmosphere and a strong magnetosphere, it could still be habitable.  If it had formed out farther from the star’s powerful flares and radiation, then it could have accumulated some ices that would melt as it migrated closer to the star.  Between these two scenarios, there is still a good chance of water existing on the exoplanet.

 

Featured Image: Artist’s impression of Proxima Centauri b

Sources: What Do We Know About Alpha Centauri?

Proxima Centauri b likely a desert world

Give Neptune a Second Chance– and hopefully some more

Throughout the late 20th and early 21st centuries, NASA has made many successful spacecraft expeditions to the Jovian planets.  Jupiter has been visited by Pioneer 10 (1972), Pioneer 11 (1973), Voyager 1 (1977), Galileo (1195-2003), and New Horizons (2007).  Saturn as well has also been visited by Pioneer 11, Voyager 1, and Cassini, which has orbited the planet since 2004 and will crash into its atmosphere later this year.  While Jupiter and Saturn received several visits from spacecrafts, the 1977 Voyager 2 expedition flew-by Uranus in 1986 and Neptune in 1989.  Since then, Voyager 2 has been the only spacecraft to visit Uranus and Neptune.  Even though observatories on Earth have made further discoveries on the icy planets, Neptune has exhibited interesting changes and abnormalities, which cannot be easily seen due to its vast distance from Earth.  In light of these mysteries, it might be time to send another spacecraft to Neptune.

There are many things scientists have yet to understand about Neptune.

  1.  Like the other gas giants, Neptune has great windy weather.  Incredibly, its winds can reach up to 500 meters per second, which is four times as fast as Jupiter’s fastest winds, and blow westward opposite its rotation.
  2. Most planets’ magnetic fields are aligned with their rotation axes.  However, along with Uranus, Neptune’s magnetosphere is misaligned from its rotation axis by about 47° and is sporadic in nature.
  3. Despite its great distance from the Sun and its -260℉ methane clouds, Neptune seems to be generating more heat internally than it receives from the Sun, which is quite unusual.
  4. Also, Voyager 2 showed that Neptune had a “Great Blue Spot,” like Jupiter’s Great Red Spot, but the spot has disappeared from view by the time observatories on Earth started to examine the planet, leaving scientists to wonder where it went.
uranus_neptune_compare
Uranus and Neptune’s off-center magnetospheres

There have been a few proposals to start expeditions, but funding has been a major obstacles.   At NASA’s request, the Jet Propulsion Laboratory has proposed sending a spacecraft to Uranus and Neptune in the 2020’s and 2030’s, but these proposals have not been finalized.   Previous plans had been announced before, but they never came into fruition.  In the 2011 decadal survey, there was a proposal to send an orbiter to Uranus, but it was set aside for the late 2020’s.  Any Neptunian spacecraft would be quite expensive itself, as it would have to rely on nuclear energy to reach the distant planet.  Presently, the plans to reach both Neptune and Uranus would each cost $2 billion dollars, so scientists have been trying to find a more cost-effective solution.  While sending a spacecraft to Neptune could prove to be a fruitful space expedition, it will take several years worth of scientific studies and peer reviews, budget revisions, and federal funding for the project to take off successfully.

Sources: The Cosmic Perspective: The Solar System- Jeffery Bennett,  Megan Donahue, Nicholas Schneider, Mark Voit

The Biggest Mysteries of Neptune- Space.com

Uranus, Neptune in NASA’s sights for new robotic mission- Spaceflight Now

Featured Image: Neptune, picture taken by Voyager 2 in August 1989

 

 

Volcanism on Io

From the four Galilean moons of Jupiter, Io stands out as having a great amount of volcanic activity.  Before it was observed via spacecraft, scientists believed all moons were cold and barren like Earth’s moon.  However, on March 8, 1979, Voyager 1 captured a mysterious plume rising from Io.  Scientists identified this as a volcanic eruption, which made Io one of the first examples of volcanic activity in outer space outside of Earth.

One of the largest visible volcanoes discovered on Io was Pele, which is named after the Hawaiian goddess.  A great red ring formed by sulfur fallout from Pele surrounds the volcano’s site, spanning 1,300 kilometers (or 808 miles) in diameter.  Pele has consistent, extremely high temperatures, so many scientists suspect the volcano contains an active lava lake, or a patera, that brings fresh lava to the surface.  The fresh lava appears to form a thin line around the volcano’s spot in a similar manner to the Hawaiian islands’ volcanoes.

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Pele the Hawaiian volcano goddess who created the Hawaiian islands

 

Io is about the size of Earth’s moon and is too small to provide heat internally, but tidal heating allows for Io’s volcanism.  Instead, Jupiter exerts tidal force on Io, as the moon goes through its elliptical orbit.  The constant tugging and change in direction generates friction and heat within the interior, leading to volcanic activity.  During an eruption from Io’s largest volcanoes, the plumes reach escape velocity and leave the moon’s atmosphere, sending its materials into the depths of space.  These materials then journey through space, either to be captured by the gravitational force of other planets and moons or to be recycled and become the future materials for new stars and worlds.

 

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Eruption from Io’s Tvashtar, captured by New Horizons/ image from NASA Photojournal

 

Sources: Tracking volcanoes on Jupiter’s moon Io

Pele Volcano and Pillan Patera

The Cosmic Perspective: The Solar System- Jeffrey Bennett, Megan Donahue, Nicholas Schneider, Mark Voit

Birth of the Solar System

For about 4 billion years, Earth has rather peacefully orbited the Sun along with its seven  fellow planets.  While this may feel how it has always been, this was not the case.  The creation of our planet and Solar System involved intense, powerful forces at work.  The video clip from Stephen Hawking’s Into the Universe series, “Formation of the Solar System,” shows how it might have looked.

Ironically, the birth of our Solar System might have begun with the deaths of many stars.  At the onset of the Big Bang, hydrogen and helium were released in a vast cloud of gas and dust called a nebula.  These nebulae created stars, which contained heavier elements and scattered their materials into new clouds when they died.  Our Solar System began with a solar nebula from a star’s supernova.  This solar nebula contained nitrogen, oxygen, iron, silicon, and many other elements, which we now see on Earth and throughout the Solar System.  Then, the cloud collapsed into itself due to gravity.

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Picture of the Crab Nebula, which shows the remains of a supernova

During the collapse, the solar nebula’s temperature increased as gas particles crashed into each other and produced thermal energy.  While gravity pulled the   cloud’s material inward from all directions, the nebula rotated at an accelerated pace, keeping the material from being all drawn to the center at once.  The particle collision and rotation caused the cloud to flatten.  The spinning, heated particles of rocks, metals, and minerals collided and clumped together into huge, rotating masses which would soon become planets.   Although the video does not explain the process, it shows how the solar nebula’s heating, spinning, and flattening created Earth.

In the center of the nebula, the temperatures became so great that the atoms began to fuse into the Sun.  When it was created, the Sun released a huge solar wind which blew the remaining gas particles into the outer edges of the Solar System.  These gas particles would get trapped by gravitational pulls of the planets Jupiter, Saturn, Uranus, and Neptune, which are now known as gas giants.  Meanwhile, the rocky terrestrial planets of Mercury, Venus, Earth, and Mars lie near the center orbiting the Sun.  Thus, our Solar System came into being.

Source: The video shows a simulated formation of the Solar System as seen in Stephen Hawking’s  Into the Universe series, clips of which can be seen in this playlist.

The Cosmic Perspective: The Solar System- Jeffery Bennett,  Megan Donahue, Nicholas Schneider, Mark Voit

Friday Night Spectacle

Tonight, on this February 10th, there is supposed to be a full moon, a lunar eclipse, and a comet, all of which are supposed to be visible.

This month’s full moon is called the “Snow Moon.”  This name came from Native American tradition, in which the full moons of each month bore different names.  However, this full moon will not be alone tonight.  Around 5:30 pm (EST), the penumbral lunar eclipse will begin.   The penumbra of Earth’s shadow, the outermost part of a shadow, will cover the Moon, dimming the pale white surface into a darker grey.  The eclipse is expected to last until 9:55 pm.  Though it may not seem as spectacular as a total lunar eclipse, seeing the shadow of our planet cover the Moon may still be an interesting experience.

In addition to the full moon and lunar eclipse, there will also be a green comet passing by Earth later tonight.  Comet 45p/Honda-Mrkos-Pajdušáková, also known as the New Year’s Comet, was discovered in 1948.  It is supposed to as closest to the Earth as it was in 2011.  Unlike the full moon, this comet is not visible to the naked eye, so a telescope or binoculars are necessary for viewing.  Hopefully, tonight’s skies will be clear enough to see the three part spectacle.  It is not likely that one can witness so much phenomena in the sky, but it is a rare sight that should not be missed.

For more on tonight:

Here’s How to Watch a Full Moon, Lunar Eclipse and Comet Light Up the Sky on Friday–TIME

A full moon, lunar eclipse, and comet–The Washington Post

Galileo’s Telescope

Most people credit Italian astronomer Galileo Galilei (1564-1642) with building the first telescope.  He did not, but he made great improvements and ingenious use of the instrument.

Before the telescope were lenses.  In the 13th century, Italian artisans created lenses for glasses to be worn by scholars with failing eyesight.  The process of making glass was difficult, as unrefined techniques left impurities, bubbles, and discoloration in the lenses.

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Tommaso da Modena using pince-nez “pinch nose” glasses

Centuries later, the Netherlands had produced a new take on the lenses.  In 1608, Hans Lippershey created the “spyglass,” a metal tube with two concave lenses which magnified objects from afar.  The original intent was for observing events from great distances unnoticed, such as reconnaissance missions and military purposes.  In 1609, Thomas Harriot tried to use the telescope to study the night sky, but the telescope was not powerful enough, equaling only three powers magnification.

Galileo had heard of Lippershey’s spyglass and sought to create his own.  He went to the Venetians, who were the greatest lensmakers in Europe at that time, and procured lenses with a 20-powers magnification.  His telescope still had major drawbacks, containing bubbles and impurities in the lenses and having a tiny field of view.  Nevertheless, he could discern oddities and aberrations in the “perfect” geocentric universe, such as craters on the Moon’s surface and  the four moons of Jupiter.  His discoveries built on the work of other contemporary heliocentric models of the universe.  Thanks to his telescope, he ultimately gave strong evidence to prove the Earth revolved around the Sun, contrary to 2000 years of astronomy believing otherwise.

Today’s telescopes are far more accurate and can see past our Solar System into the depths of outer space.  Galileo’s telescope could not even capture half of the Moon’s surface.  In spite of all its imperfections, however,the device did its job beautifully and led to revolutionary astronomical observations.   The fact remains that the telescope invented by Galileo forever changed the study of astronomy.

Source: For more on the history of the telescope–A history of the telescope- Ars Technica