A Sunny Cold Sunday is a Good Day to Find Sun Dogs

When the temperature is just right, and the sky is clear, you can see some amazing phenomenon from the Sun.  It isn’t your eyes playing a trick on you, it just means you’re seeing the right conditions for a really amazing experience.

Sundogs in the morning

Sun Dogs, known scientifically as Parhelia, typically appear as two bright patches on either side of the Sun.  Occasionally they reveal rainbow colours in their pattern, but can be quite bright.  They are most easily visible when the Sun is low in the sky.

Sun Dogs are made from the refraction of ice crystals in the upper atmosphere.  They are visible in any season anywhere in the world, but are more common in winter conditions, as ice crystals can form lower in the atmosphere.

Flat hexagonal ice crystals act as tiny prisms that bend light at a minimum angle of 22 degrees, and if randomly oriented in the atmosphere, they will produce a solar halo, essentially a complete ring around the Sun.  But when it is colder, the crystals can sink in the atmosphere, causing them to align themselves vertically, resulting in horizontal refraction, and focussing the bright spots as Sun Dogs on either side of the Sun.

Making Sundogs

So if you feel like getting up early this Winter to enjoy some rare sunshine, you can rest assured that there’s nothing magical about what you’re seeing.  Just some science!

Opportunity Mars Panorama Marks 11 Years

The Opportunity rover has just about reached it’s 11 year anniversary of it’s 90 day mission puttering around Mars.  The actual day is tomorrow since the rover landed on January 25th, 2004.

To mark its incredible accomplishment, the imaging team produced a lovely panorama of what the rover would see from its current position on a high point along the rim of endeavour crater.

Click the image for full size. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

The map below shows the path of Opportunity over its past 11 years, from the Eagle crater, to endurance crater, to Victoria crater, and finally on to the much more massive Endeavour crater, where it currently sits near the site named Cape Tribulation.  This is the spot where the rover captured the panorama.

Opportunity also holds the record for longest distance travelled on any other world.  This is especially amazing because it beat all of the records of Lunar rovers, and has covered nearly the distance of a marathon, 42 Km.

Opportunity wins the Race! Credit: NASA/JPL-Caltech

Opportunity has definitely had to face adversity over the course of its time on Mars.  In April 2005, the rover was stuck in a sand dune until June, when the mission team was finally able to free it.  It’s wheels had suck ddep into the Martian soil, but it kept on fighting.

Credit: NASA/JPL-Caltech

The rover has accomplished it’s main scientific goals, including the study of various rocks along different sites to determine the history of water on the red planet.  It continues to explore sites along the rim of the endeavour crater, searching for clues about the geological history of Mars, taking atmospheric measurements, and showing us what humanity can accomplish when we work together with a focus on scientific advancement.



Heavy Metal Frost on Venus?

Venus is the most hellish place I know of in the Solar System, and maybe even the broader Universe.  Even though Venus looks pretty harmless and is named for the Roman goddess of Love, beneath the soft looking clouds lies sulphuric acid rainfall, 450 degree surface temperatures, and crushing pressure 90 times the atmospheric pressure of Earth at sea level.

Venus in Visible

Venus minus the clouds

How do we get the surface picture of Venus above? NASA’s Magellan probe in 1994 finished mapping the surface by looking at Radio wavelengths emitted by the planet and using radar to bounce waves off the surface to measure features.

Though Magellan came up with some interesting results.  It found that higher elevation areas of the surface such as highlands reflected radar very well, but at the highest elevations the radar results eventually turned black, meaning there was no radio wave reflection. Why?

Through the last twenty years since the Magellan maps have been made, no one has been able to figure out why this is happening. Currently scientists have two schools of thought on the subject.  It’s either ‘frost’ made from heavy metals, or ferroelectric crystals.

Just like on Earth, the highlands of Venus are cooler than the lowlands.  This temperature difference could lead to a build-up of frost on Venus’ highlands, that would not be seen at lower elevations.  It would also be radio bright as it would be very reflective, in the same way that frost on Earth reflects visible light into space.  Of course Venus is far too hot to have frost made of water, rather the Venusian frost would be made of metallic compounds such as coloradoite (which consists of mercury and tellurium) and tellurobismuthite (which is made of bismuth and tellurium).  These would be radio bright regardless of elevation.

The other possibility is that crystals on Venus have separated positive and negative electric charges, effectively making one side of the crystal positive and the other negative. These ferroelectric crystals, as they’re called, have properties that depend on temperature.  Research suggests that these crystals would be radio bright until they reached a certain temperature, and then they would stop reflecting radio waves at the highest elevations.

Whatever it is that’s causing the strange radio behaviour on Venus, one thing is certain.  It is very hard to test the properties of elements on a planet with such a high pressure and hot environment.  There may be a yet-unknown crystal on Venus that is creating these strange conditions.

We will have to send a probe again someday, though Venus has a history of eradicating any probe we send in approximately an hour.  So until we find a way to produce a much tougher probe, or we find a way to justify millions of dollars for an hour long science gathering mission, Venus will remain a mystery.


Space News: Photos of the Week

This week there were just too many fantastic photo releases to pick just one and stick with it, so here are some of the great stories popping up with fantastic images to accompany them:

Fine Detail From Rosetta on 67P

Credit: ESA Rosetta

This amazing shot from the Rosetta orbiter shows such incredible detail as comet 67P catches light from the sun.  The shadows are what makes this image spectacular as you can see so many fine features.  The other noteworthy part of the image is the bright streaks of material coming off the comet in the background.  As the comet and the orbiter move closer to the Sun, the warming rays will melt the ices and liberate gas and dust from the comet, eventually becoming a bright coma.  I can’t wait until those photos come in.

South Pole Storms on Venus

Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford.

From the Venus Express mission’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) comes a brilliant photo of the Polar Vortex discovered in 2006.  Venus Express has kept a close eye on the storm since then, seeing it change shape and swirl.  Here is a composite video made from images of the vortex.

Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. of Oxford

The vortex is a result of warm air rising in the Venutian atmosphere and then spiralling down to the poles, where it cools and sinks.  The winds of Venus are very fast up in the high atmosphere, yet very calm near the surface.

Comet Lovejoy For all to See

Credit: Velimir Popov & Emil Ivanov (IRIDA Observatory)

You could assume that after nearly two weeks I am tired of seeing so many photos of the same comet.  But the beauty is that easy photographer reveals different perspective and detail in the 4th-magnitude traveller.  It really speaks to the fact that with any subject or scene, photographers are distinct and no camera will ever capture exactly the same thing.  The spectacular image above shows the bright coma and the intense details of the comet tail.

Credit: Lynn Hilborn

As a bonus, I had to post this amazing image showing an Atlas V launch of a US Navy satellite with the Universe behind it.  So many features are visible in this incredibly wide-field image.  Just above the streak of the rocket is the brightest star in the night sky, Sirius.  Above that lies the familiar constellation of Orion with red star Betelgeuse and blue star Rigel, as well as the famed Orion nebula and faint Barnard’s Loop nebula visible.  Keep going up higher and you can see the bright star Aldebaran with the Hyades cluster as it’s backdrop, and then further to the compact young blue stars of the Pleiades cluster.  Finally the visiting comet Lovejoy is at the top of the image, giving us perspective on how vast the tail of the comet really is.



From One distant World to Another: How the Ocean Floor is Giving New Insight into Supernovae

I always like to bring up the crazy ways in which two areas of science that seem completely disconnected can relate to each other, occasionally giving incredible insights.

By looking at the ocean floor, a world human beings can’t reach without special pressurized equipment, we are learning about space, a world human beings can’t reach without special pressurized equipment.

So how is the ocean teaching us about space?

Physicists at the Australian National University have been studying seafloor dust that has been raining down on Earth as micrometeorites over the past 25 Million years.  The dust is thought to originate from ancient supernova explosions, and by studying the heavy elements present, we are gaining new insight into which elements are being formed by supernovae.

“Small amounts of debris from these distant explosions fall on the earth as it travels through the galaxy,” said lead researcher Dr Anton Wallner, from the Research School of Physics and Engineering.

The current theory of supernovae is that they produce elements essential for life on Earth, such as Potassium and Iodine, as well as other heavy elements, such as Gold, Silver, Lead, and Plutonium.  Without ancient supernova explosions, life on Earth could never have developed.

The research team studied Plutonium 244 in the first ten cm of ocean floor crust, corresponding to a 25 Million year period of dust deposits.  Plutonium 244 is used as a radioactive clock since it undergoes radioactive decay with a half life of 81 Million years.  “Any plutonium-244 that existed when the earth formed from intergalactic gas and dust over four billion years ago has long since decayed,” Dr Wallner said. “So any plutonium-244 that we find on earth must have been created in explosive events that have occurred more recently, in the last few hundred million years.”

The surprising result is that the research team found 100 times less Plutonium 244 than they were expecting, based on the number of supernovae and the time-scale required for their dust to reach Earth.  According to Dr. Wallner “It seems that these heaviest elements may not be formed in standard supernovae after all. It may require rarer and more explosive events such as the merging of two neutron stars to make them.”

This conclusion raises questions about where the heavier radioactive elements are produced.  Maybe they aren’t produced in all supernovae, as was originally thought.  Perhaps only certain types of supernova explosions are energetic enough to produce the heaviest elements in the Universe.  Or maybe, supernovae don’t produce these elements at all, and we need mergers of neutron stars or black holes to synthesize them.

It’s a reminder that just because two fields of science seem disconnected, it doesn’t mean that they are not related in some fantastic way.  Maybe we just haven’t found the connection yet.  It truly points to the interconnected nature of all things in the Universe.