Astronomers celebrate Neptune’s Birthday!

Image of Neptune Planet NASA
Image of Neptune showing the Great Dark Spot – Courtesy NASA

Neptune turned “one year” old yesterday when it completed its first revolution around the sun since its discovery 165 years ago. Astronomy world celebrated this event as Neptune completed its one year which is 164.79 earth years yesterday. Named after the Roman Sea God, the 8th and last planet of our Solar System, Neptune’s location was mathematically predicted and discovered by Urbain Le Verrier, John Couch Adams and Johann Gottfried Galle putting an end to decades old question “Who was tugging on Uranus?”

Galileo observed Neptune on December 28, 1612 and again on January 27, 1613 and recorded the findings in his drawings. However, he is not credited with the discovery of the planet since he mistook Neptune as a distant star that appeared in conjunction with Jupiter. Neptune had turned retrograde on the day when Galileo discovered it, however, according to physicist David Jamieson, Galileo was at least aware that the “star” he discovered moved relative to the fixed starts.

Substantial deviations from astronomical tables of Uranus’s orbit published in 1821 by French astronomer Alexis Bouvard was subsequently observed leading him to hypothesise that an unknown body was perturbing the orbit of Uranus through gravitational interaction.  British astronomer John Couch Adams in 1843, began work on Uranus’s orbit using the data sent to him by the then Astronomer Royal Sir George Airy through James Challis, the then Cambridge Observatory director. His mathematical work through 1845-46 produced several estimates of the existence a new planet.

Image of Neptune's Orbit
Neptune’s Orbit compared to other planet – Courtesy Wikipedia

During the same period, French astronomer Urbain Le Verrier independently developed his own calculations about the new planet but did not stimulate enthusiasm in his fellow astronomers. In June 1846, Sir George Airy, upon seeing the similarity of Le Verrier’s first published estimate of the planet’s longitude to that of Adams’s estimate, Airy persuaded James Challis to search for the planet though the search that lasted throughout August and September of that year did not produce any results.

Meanwhile, a letter was sent to the German astronomer Johann Gottfried Galle of Berlin Observatory by Le Verrier requesting him to search for the new planet using the observatory’s refractor. A student at the observatory, Heinrich d’Arrest suggested to Galle that they might be able to make the discovery if they compared the chart drawn about the region predicted by Le Verrier and with the current sky to seek the displacement characteristic of the planet as opposed to a fixed star.  It worked and that very evening on September 23, 1846, Neptune was discovered within 1° of where Le Verrier had predicted and about 12° from Adams’ prediction. James Challis later realised that he did observe the planet twice in August but failed to identify it due to his casual approach to the work.

There have been much debate between France and Great Britain as to who should get the credit of the discovery of the planet. However, it was decided through international consensus that both Adams and Le Verrier should be credited equally even though to this day there are people who do not credit Adams with the discovery.

Image of Neptune by Hubble
Neptune shot by Hubble at four time intervals – Courtesy NASA

Neptune is 2.8 billion miles from the Sun which is about 30 times farther than Earth making it slow and freezing cold.  The image shows the planet in four hour intervals within Neptune’s 16-hour day. The white fluffy streaks are clouds, but not of the Earth variety. Due to the low ambient temperature of the planet, they are high-altitude swaths of frozen methane. Neptune has a 29-degree tilt, which, like Earth’s tilt of 23-degrees, causes the planet to experience seasons. Currently Neptune is experiencing summer in the southern hemisphere and winter in the north. While a season lasts only a few months on Earth, it lasts up to 40 years on Neptune.

Planetary scientist Dr. Craig O’Neil of Macquarie University says that we still haven’t learned much about Neptune since its discovery.  “It’s location at the edge of the solar system makes it a bit of a black hole from a knowledge point of view,” he says. According to him, the huge distance from the sun makes sun look like a point of light in Neptune no brighter than Venus does from Earth. Most of what we know about Neptune today comes from Voyager 2’s fly-by of the planet in 1989 and the Hubble Space Telescope.

Image of Neptune Rings
Neptune’s Rings shot by Voyager 2 in 1989 – Courtesy Wikipedia

Neptune does have a planetary ring system, though it is less substantial than that of Saturn. The rings may consist of ice particles coated with silicates or carbon-based material giving them a reddish hue. The three main rings are the narrow Adams Ring, 63000 km from the centre of Neptune, the Le Verrier Ring, at 53000 km, and the broader, fainter Galle Ring, at 42000 km. A faint outward extension to the Le Verrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57000 km. Observations show that the rings are more unstable than previously thought. Images taken from the W. M. Keck Observatory in 2002 and 2003 show considerable decay in the rings compared to images by Voyager 2.

Most of the atmosphere of Neptune is made of hydrogen, helium and methane. The blue colour supposedly comes from methane absorbing red light. However, Uranus, that has a similar atmosphere is cyan in colour. Scientists are still speculating about the supersonic winds of Neptune which are the fastest in the Solar System since their speed of 2,000 kilometres per hour do not conform to the large distance from the sun.

The Sun can’t be powering what’s happening there. Given Uranus has fairly mild winds, Neptune’s dynamics are a mystery. One idea is that if you put methane under enough pressure deep in Neptune’s atmosphere, it could convert to diamond which would fall as rain. This conversion process releases heat which could power the winds. That’s a little more speculative, but speculation is all we’ve got, ” says Dr. O’Neil.

Image of Neptune's Moons by Hubble
Neptune’s Moons by Hubble – Courtesy NASA

Shown above is a composite image of Hubble shots stitched together by NASA. You can see multiple moons within the same orbit due to the time lapse between shots. In order to get the true hue of Neptune’s atmosphere, NASA took numerous photos with three different colour filters. Over 30 moons have been discovered orbiting Neptune but the majority orbit farther away to fit into this shot.

2005 YU55 to arrive on November 8, 2011

Discovered by Robert McMillan of the Spacewatch Program near Tucson, Arizona on December 28, 2005, the third near-earth asteroid of 2011, named 2005 YU55 will pass between the Moon and the Earth on November 8. The dark, near spherical rock of 400 meters diameter will move as close as 0.85 lunar distances from earth, confirmed NASA marking it the closest approach to date by an object this large that we know about in advance.

Image of 2005 YU55 Approach
2005 YU55 Approach (Click image to see animation)

Though classified as a potentially hazardous object, 2005 YU55 poses no threat to Earth for at least the next 100 years, reported NASA’s Neart Earth Object Program.

The approach of 2011 MD had created a news earlier this week, when it passed roughly 7,500 miles close to Earth. Earth’s gravity sharply altered its trajectory, preventing it from hitting the planet. However, the International Astronomical Union’s Minor Planet Center in Massachusetts, USA did put out an alert.

According to space scientist Clark Chapman of the Southwest Research Institute in Boulder, Colorado, USA, there is a roughly 50 percent chance of a 30-meter-plus asteroid striking Earth each century. We can expect the next event of this type in 2028 when asteroid (153814) 2001 WN5 will pass within 0.6 lunar distances to earth.

2011 MD leaves warning to Earthlings

Image of 2011 MD Path
2011 MD Trajectory

The Asteroid 2011 MD, discovered on 22nd at the LINEAR near-Earth object survey in Socorro, New Mexico by the amateur Australian Astronomer, Peter Lake flew by the Earth on 27th at a close proximity of 7600 miles which is closer than most satellites. The approach did startle scientists but the prospect of the asteroid burning up in the atmosphere on entry was a relief.

The asteroid flew over the southern Atlantic Ocean, off the coast of Antarctica, during its closest approach. Though a relief now, such rocks are expected to brush Earth every once in six years. As part of the program to identify potentially hazardous objects, scientists are tracking threats like these regularly.

In February, 2011 CQ1, detected just 14 hours before approach passed even closer with a proximity of 3,400 miles making it the closest known flyby asteroid till date. You can view the images of 2011 MD captured by astronomer Tom Glinos and Wireless Beehive website here and here.

2011 MD belongs to a class of asteroids known as Apollo Asteroids that are known to be “Earth Crossers“.  Their orbital semi-major axes are greater than that of the Earth (> 1 AU) and the perihelion distance (q) is less than 1.017 AU. Initially thought of as a space junk, the asteroid gave only a brief period of observability since it appeared close to the Sun during its nearest approach.

The bigger news is that a larger 400m asteroid named 2005 YU55, will make a close return on November 8. However, it is already being tracked by JPL’s NEO scientists in addition to over 75 rocks on the watch list that might make close approach to earth between now and mid-October. Asteroids like these remind us about our vulnerability to an impact and to prepare the technology to thwart such an incident if it happens.

A note on the Fermi-Hart Paradox!

The Habitable Zone

The Habitable Zone around a star

The future of humanity looks bleak and bright at the same time depending on how we perceive it. If we look around, we may feel that we are moving forward towards a brighter tomorrow. However, if you look up, the thoughts change. The sky on a clear night is one of the most beautiful sights you can get on Earth but this awe inspiring sight brings questions into our minds regarding the bleak future of human race. Whether we are alone in the universe is a question that might give us clues about our own fate in the distant future. We can hope to grow so advanced that we wouldn’t have to look back or we can expect ourselves to fall back and perish. SETI scientists spend their entire lives with radio telescopes pointed at the sky listening to the “cosmic buzz” hoping to find evidence that there is intelligent life outside Earth. The Drake Equation gives different estimates regarding the number of intelligent civilizations outside depending on whether it is an optimist or a pessimist who substitutes the values. However to this day, there hasn’t been any conclusive evidence that there is life outside out planet.

This paradox first postulated by Enrico Fermi and later examined by Michael H. Hart, analyzes various reasons why there haven’t been any intelligent exobiology detected so far.

The Drake Equation – Predicts the number of civilizations in the galaxy

The statement made by the Fermi-Hart Paradox is as follows:

The apparent size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this hypothesis seems inconsistent with the lack of observational evidence to support it.

So why is it that despite the size of the universe, we haven’t seen intelligent life outside earth yet? Two corollaries of the Fermi-Hart paradox may give us some clues. They are the Doomsday argument and Von Neumann Probe.

According to the Doomsday Argument, we ask ourselves, Is it the nature of intelligent life to destroy itself?

This theme has been extensively explored in science as well as science fiction alike and deals with an argument that precludes the possibility of a technological civilization with an invariable proclivity to destroy themselves shortly after developing radio or space technology. The various postulated means of annihilation include biological and nuclear warfare, nano-technological catastrophe, accidental contamination, a badly programmed super-intelligence, ill-advised physics experiments or a Malthusian Catastrophe that deteriorates the planet’s ecosphere.

Probabilistic argumetns have bene put forward suggesting human extinction as an inevitable event happening sooner than later. Sagan and Shklovsky suggested in 1966 that either a technological civilization will destroy itself within a century after developing interstellar communicative capability or will master their self destructive tendencies and survive for billions of years.

An inhabitable planet

Gliese 581c – An exoplanet within the Goldilock zone of its star

Thermodynamics and chaos theory may also suggest clues regarding the tendency to self annihilate. As far as life can evolve as an ordered system, it may not create a problem but when it starts with its interstellar communicative phase, the system would probably get unstable and eventually self destruct.

Self destruction is a paradoxical outcome of evolutionary process in a Darwinian point of view. Evolutionary psychology suggests that at a time when humans competed for scarce resources, they were subjected to aggressive instinctual drives like tendency to consume resources, extend longevity and to reproduce which eventually led to a more technological society which may drive us to extinction. Self destruction of a technological civilization, according to Fermi, might be a universal occurrence. Self destruction may not be the only outcome though. There is a remote possibility of the civilization getting back to being non-technological as we saw happening to the Ba’ku people in the movie Star Trek: Insurrection.

A Flying Saucer – An alien craft?

A slightly different question is posed by the Von Neumann probe which asks, Is it the nature of intelligent life to destroy others?

This postulate investigates the possibility of a technological civilization, once it reaches a certain level of technological capability, destroys other intelligence when they appear. This concept has also been explored in science fiction for decades. The causes of such extermination might be expansionism, paranoia or plain aggression. Cosmologist Robert Harrison added a corrolary to Sagan and Shklovsky’s suggestion in 1981 by arguing that given a technological species that has overcome its own tendency to self destruct, it will view other species in the universe as a virus and try to exterminate them. A direct consequence of this argument is the picture of an intelligent being as a super-predator, just as humans are today.

Von Neumann Probe

Extracting a star’s energy – An example of a Von Neumann Probe

Just like exploration, extermination of other civilizations can be carried out using self-replicating artificial probes. It is a more dangerous case since even after the civilization that created such probes have died out, these probes will continue to do the job their creators assigned to them. If take this possibility into consideration, then that might answer the scarcity of observational evidence of extraterrestrial intelligence, because either these probes will destroy them, force them to be quiet or force them to live in hiding to prevent detection.

Leaving all these arguments aside, there is still a very high probability that we are indeed alone in this universe. To conclude, what is going to be our future? Are we heading towards self destruction? Is our life and society as ephemeral as that of a mayfly? Are the advancements we make every day in technology actually the nails we are driving into our own coffins? Or are we going to be like the Borgs? I leave this up to you to answer.


Fermi Paradox
Risks to civilization
Article by Fraser Cain
Living in a killing world
Margaret Atwood
Memory Alpha on Borg
Wikipedia on Malthusian Catastrophe