We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.
You can join in the discussion between episodes over at our Weekly Space Hangout Crew group in G+, and suggest your ideas for stories we can discuss each week!
Comet Lovejoy on Feb. 7, 2015 as seen from Payson, Arizona. Credit and copyright: Chris Schur.
With the Moon rising later in the evening this weekend, astrophotographers have taken some spectacular pictures of Comet 2014 Q2 Lovejoy, which continues shine on! Enjoy a few photos here and check out more in Universe Today’s Flickr page.
Chris Schur from Payson, Arizona took the above image with a 80mm f/4.6 Zeiss APO and a ST10xme ccd camera.
Comet Lovejoy on February 8, 2015 seen with a 12.5″ Newtonian from Payson, Arizona. Credit and copyright: Chris Schur.Comet C/2014 Q2 Lovejoy, Widefield view, false color. Feb 8, 2015. Credit and copyright: Joseph Brimacombe.
[caption id="attachment_118887" align="aligncenter" width="580"] Comet Lovejoy Q2, Feb 7, 2015. Credit and copyright: Cajun Astro on Flickr.
C/2014 Q2 Lovejoy comet passing over perseus and Taurus molecular cloud forming a triangle with the California Nebula (the red nebula on the left), the M45 Pleaides and Hyades in Taurus. Taken on January 14, 2015 from Pragelato, Turin, Italy. Credit and copyright: Leonardo Orazi.
Last night was the first time I was able to spot Comet Lovejoy with unaided eyes. The latest images from our readers and dedicated astrophotographers confirm that now is a good time to see the comet, which is reaching maximum brightness at his week. Spaceweather.com reports that many experienced observers say the comet is now shining at magnitude +3.8. With clear, dark skies C/2104 Q2 is easily seen with binoculars.
Enjoy this gallery of recent images, and if you’ve taken an image, consider joining our Flickr pool and submitting it. We may use your image in an upcoming article!
Comet Lovejoy C/2104 Q2 cruising past the open star Cluster M45 “Pleiades” or “The Seven Sisters.” Credit and copyright: John Chumack.Comet Lovejoy taken on January 15, 2015 from Singapore. Credit and copyright: Justin Ng.Comet C/2014 Q2 Lovejoy in a widefield false color image taken on January 16, 2015 from New Mexico Skies. Credit and copyright Joseph Brimacombe.Comet Lovejoy, C/2014 Q2, a wide binocular field west of M45, the Pleiades star cluster in Taurus, on January 15, 2015, shot from Silver City, New Mexico. The long blue ion tail stretched back for about 8°. Credit and copyright: Alan Dyer.Comet Lovejoy photographed from Torrance Barrens Dark-Sky Preserve (30 km from Gravenhurst, Ontario, Canada; 200 km north of Toronto) on January 13, 2015. Credit and copyright: Michael Watson. Comet Lovejoy as seen from Lahore, Pakistan on January 15, 2014, 10:30 pm local time. 35 single images stacked in DSS. Each 8 seconds, ISO 2000, f/5.6, edited in Photoshop. Credit and copyright: Roshaan BukhariHigh resolution 3 panel mosaic of C/2014 Q2 on January 11, 2015. Field of view is approximately 3.5° x 2° and composed of three fields. Many fine streamers are visible emanating from the nucleus. Credit and copyright: SEN/ Damian Peach.Comet LoveJoy photographed from Kosovo on January 13, 2015. Credit and copyright: Suhel A. Ahmeti.C2014 Q2 Lovejoy on January 13, 2015. Credit and copyright: Shahrin Ahmad. Comet Lovejoy on January 11, 2015. Credit and copyright: Henry Weiland.Wide angle shot of Comet Lovejoy with the constellation Orion, showing rich fields of red nebula, star clouds and dark nebula with the bright green naked eye comet. Credit and copyright: Chris Schur.Comet Lovejoy traveling through Taurus. Imaged on January 12, 2015 from Bathurst, New South Wales. Credit and copyright: Wes Schulstad.C2014 Q2 Lovejoy on January 7, 2015, taken from Bannister Green, England. Credit and copyright: Wendy Clark.
As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska
Think of all the different horizons humans have viewed on other worlds. The dust-filled skies of Mars. The Moon’s inky darkness. Titan’s orange haze. These are just a small subset of the worlds that humans or our robots landed on since the Space Age began.
It’s a mighty tribute to human imagination and engineering that we’ve managed to get to all these places, from moons to planets to comets and asteroids. By the way, for the most part we are going to focus on “soft landings” rather than impacts — so, for example, we wouldn’t count Galileo’s death plunge into Jupiter in 2003, or the series of planned landers on Mars that ended up crashing instead.
The Moon
Al Shepard raises the American flag during Apollo 14 in February 1971. Below is the shadow of his crewmate, Ed Mitchell. Credit: NASA
Our instant first association with landings on other worlds is the human landings on the Moon. While it looms large in NASA folklore, the Apollo landings only took place in a brief span of space history. Neil Armstrong and Buzz Aldrin were the first crew (on Apollo 11) to make a sortie in 1969, and Apollo 17’s Gene Cernan and Jack Schmitt made the final set of moonwalks in 1972. (Read more: How Many People Have Walked on the Moon?)
But don’t forget all the robotic surveyors that came before and after. In 1959, the Soviet Union’s Luna 2 made the first impact on the lunar surface; the first soft landing came in 1966, with Luna 9. The United States set a series of Ranger and Surveyor probes to reach the moon in the 1960s and 1970s. The Soviet Union also deployed a rover on the moon, Lunakhod 1, in 1970 — the first remote-controlled robot controlled on another world’s surface.
In 2013, China made the first lunar soft landing in a generation. The country’s Chang’e-3 not only made it safely, but deployed the Yutu rover shortly afterwards.
Mars
Sojourner – NASA’s 1st Mars Rover. Rover takes an Alpha Proton X-ray Spectrometer (APXS) measurement of Yogi rock after Red Planet landing on July 4, 1997 landing. Credit: NASA
Mars is a popular destination for spacecraft, but only a fraction of those machines that tried to get there actually safely made it to the surface. The first successful soft landing came on Dec. 2, 1971 when the Soviet Union’s Mars 3 made it to the surface. The spacecraft, however, only transmitted for 20 seconds — perhaps due to dust storms on the planet’s surface.
Less than five years later, on July 20, 1976, NASA’s Viking 1 touched down on Chryse Planitia. This was quickly followed by its twin Viking 2 in September. NASA has actually made all the other soft landings to date, and expanded its exploration by using rovers to move around on the surface. The first one was Sojourner, a rover that rolled off the Pathfinder lander in 1997.
NASA also sent a pair of Mars Exploration Rovers in 2004. Spirit transmitted information back to Earth until 2010, while Opportunity is still roaming the surface. The more massive Curiosity lander followed them in 2012. Another stationary spacecraft, Phoenix, successfully landed close to the planet’s north pole in 2008.
Venus
Surface of Venus by Venera.
Venera 7 — one of a series of Soviet probes sent in the 1960s and 1970s — was the first to make it to the surface of Venus and send data back, on Dec. 15, 1970. It lasted 23 minutes on the surface, transmitting weakly towards Earth. This may have been because it came to rest on its side after bouncing through a landing.
The first pictures of the surface came courtesy of Venera 9, which made it to Venus on Oct. 22, 1975 and sent data back for 53 minutes. Venera 10 also successfully landed three days later and sent back data from Venus as planned. Several other Venera probes followed, most notably including Venera 13 — which sent back the first color images and remained active for 127 minutes.
Titan
Artist depiction of Huygens landing on Titan. Credit: ESA
Humanity’s first and only landing on Titan so far came on Jan. 14, 2005. The European Space Agency’s Huygens probe likely didn’t come to rest right away when it arrived on the surface, bouncing and skidding for about 10 seconds after landing, an analysis showed almost a decade later.
A fish-eye view of Titan’s surface from the European Space Agency’s Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona
The probe managed to send back information all the way through its 2.5-hour descent, and continued transmitting data for an hour and 12 minutes after landing. Besides the pictures, it also sent back information about the moon’s wind and surface.
The orangey moon of Saturn has come under scrutiny because it is believed to have elements in its atmosphere and on its surface that are precursors to life. It also has lakes of ethane and methane on its surface, showing that it has a liquid cycle similar to our own planet.
Comets and asteroids
Images from the Rosetta spacecraft show Philae drifting across the surface of its target comet during landing Nov. 12, 2014. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Robots have also touched the ground on smaller, airless bodies in our Solar System — specifically, a comet and two asteroids. NASA’s NEAR Shoemaker made the first landing on asteroid Eros on Feb. 12, 2001, even though the spacecraft wasn’t even designed to do so. While no images were sent back from the surface, it did transmit data successfully for more than two weeks.
Japan made its first landing on an extraterrestrial surface on Nov. 19, 2005, when the Hayabusa spacecraft successfully touched down on asteroid Itokawa. (This followed a failed attempt to send a small hopper/lander, called Minerva, from Hayabusa on Nov. 12.) Incredibly, Hayabusa not only made it to the surface, but took off again to return the samples to Earth — a feat it accomplished successfully in 2010.
The first comet landing came on Nov. 12, 2014 when the European Space Agency’s Philae lander successfully separated from the Rosetta orbiter and touched the surface of Comet 67P/Churyumov–Gerasimenko. Philae’s harpoons failed to deploy as planned and the lander drifted for more than two hours from its planned landing site until it stopped in a relatively shady spot on the comet’s surface. Its batteries drained after a few days and the probe fell silent. As of early 2015, controllers are hoping that as more sunlight reaches 67P by mid-year, Philae will wake up again.
Illustration of a rocky planet being bombarded by comets. (Image credit: NASA/JPL-Caltech)
Where did all of our water come from? What might seem like a simple question has challenged and intrigued planetary scientists for decades. So results just released by Rosetta mission scientists have been much anticipated and the observations of the Rosetta spacecraft instruments are telling us to look elsewhere. The water of comet 67P/Churyumov-Gerasimenko does not resemble Earth’s water.
Because the Earth was extremely hot early in its formation, scientists believe that Earth’s original water should have boiled away like that from a boiling kettle. Prevailing theories have considered two sources for a later delivery of water to the surface of the Earth once conditions had cooled. One is comets and the other is asteroids. Surely some water arrived from both sources, but the question has been which one is the predominant source.
There are two areas of our Solar System in which comets formed about 4.6 billion years ago. One is the Oort cloud far beyond Pluto. Everything points to Comet 67P’s origins being the other birthplace of comets – the Kuiper Belt in the region of Neptune and Pluto. The Rosetta results are ruling out Kuiper Belt comets as a source of Earth’s water. Previous observations of Oort cloud comets, such as Hyakutake and Hale-Bopp, have shown that they also do not have Earth-like water. So planetary scientists must reconsider their models with weight being given to the other possible source – asteroids.
The question of the source of Earth’s water has been tackled by Earth-based instruments and several probes which rendezvous with comets. In 1986, the first flyby of a comet – Comet 1P/Halley, an Oort cloud comet – revealed that its water was not like the water on Earth. How the water from these comets –Halley’s and now 67P – differs from Earth’s is in the ratio of the two types of hydrogen atoms that make up the water molecule.
Illustration of the Rosetta spacecraft showing the location of the ROSINA mass spectrometer instrument, DFMS. The difference between a Deuterium and Hydrogen atom is also illustrated. A water molecule with Deuterium is known as heavy water due to the additional mass of Dueterium vs. Hydrogen (i.e., an extra neutron). (Credit: ESA/Rosetta)
Measurements by spectrometers revealed how much Deuterium – a heavier form of the Hydrogen atom – existed in relation to the most common type of Hydrogen in these comets. This ratio, designated as D/H, is about 1 in 6000 in Earth’s ocean water. For the vast majority of comets, remote or in-situ measurements have found a ratio that is higher which does not support the assertion that comets delivered water to the early Earth surface, at least not much of it.
Most recently, Hershel space telescope observations of comet Hartley 2 (103P/Hartley) caused a stir in the debate of the source of Earth’s water. The spectral measurements of the comet’s light revealed a D/H ratio just like Earth’s water. But now the Hershel observation has become more of an exception because of Rosetta’s latest measurements.
A plot displaying the Deuterium/Hydrogen (D/H) ratio of Solar System objects. Asteroids have a D/H ratio that matches that of the Earth, while comets – except for two measured to date – have higher ratios. Objects are grouped by color: planets & moons (blue), chrondritic meteorites from the asteroid belt (grey), Oort cloud comets (purple), and Jupiter family comets (pink). Diamond markers = In Situ measurements; circles = remote astronomical measurements. (Credit: Altwegg, et al. 2014)
The new measurements of 67P were made by the ROSINA Double Focusing Mass Spectrometer (DFMS) on board Rosetta. Unlike remote observations using light which are less accurate, Rosetta was able to accurately measure the quantities of Deuterium and common Hydrogen surrounding the comet. Scientists could then simply determine a ratio. The results are reported in the paper “67P/Churyumov-Gerasimenko, a Jupiter Family Comet with a high D/H ratio” by K. Altwegg, et al., published in the 10 December 2014 issue of Science.
New Rosetta mission findings do not exclude comets as a source of water in and on the Earth’s crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager)
The ROSINA instrument observations determined a ratio of 5.3 ± 0.7 × 10-4, which is approximately 3 times the ratio of D/H for Earth’s water. These results do not exclude comets as a source of terrestrial water but they do redirect scientists to consider asteroids as the predominant source. While asteroids have much lower water content compared with comets, asteroids, and their smaller versions, meteoroids, are more numerous than comets. Every meteor/falling star that we see burning up in our atmosphere delivers a myriad of compounds, including water, to Earth. Early on, the onslaught of meteoroids and asteroids impacting Earth was far greater. Consequently, the small quantities of water added delivered by each could add up to what now lies in the oceans, lakes, streams, and even our bodies.
The Earth is often compared to a majestic blue marble, especially by those privileged few who have gazed upon it from orbit. This is due to the prevalence of water on the planet’s surface. While water itself is not blue, water gives off blue light upon reflection.
For those of us confined to living on the surface, the fact that our world is mostly covered in water is a well known fact. But how much of our planet is made up of water, exactly? Like most facts pertaining to our world, the answer is a little more complicated than you might think, and takes into account a number of different qualifications.
Sources of Water:
In simplest terms, water makes up about 71% of the Earth’s surface, while the other 29% consists of continents and islands. To break the numbers down, 96.5% of all the Earth’s water is contained within the oceans as salt water, while the remaining 3.5% is freshwater lakes and frozen water locked up in glaciers and the polar ice caps.
Of that fresh water, almost all of it takes the form of ice: 69% of it, to be exact. If you could melt all that ice, and the Earth’s surface was perfectly smooth, the sea levels would rise to an altitude of 2.7 km.
Illustration showing all of Earth’s water, liquid fresh water, and water in lakes and rivers. Credit: Howard Perlman, USGS/illustraion by Jack Cook, WHOI
Aside from the water that exists in ice form, there is also the staggering amount of water that exists beneath the Earth’s surface. If you were to gather all the Earth’s fresh water together as a single mass (as shown in the image above) it is estimated that it would measure some 1,386 million cubic kilometers (km3) in volume.
Meanwhile, the amount of water that exists as groundwater, rivers, lakes, and streams would constitute just over 10.6 million km3, which works out to a little over 0.7%. Seen in this context, the limited and precious nature of freshwater becomes truly clear.
Volume vs. Mass:
But how much of Earth is water – i.e. how much water contributes to the actual mass of the planet? This includes not just the surface of the Earth, but inside as well. In terms of volume, all of the water on Earth works out to about 1.386 billion cubic kilometers (km³) or 332.5 million cubic miles (mi³) of space.
But in terms of mas, scientists calculate that the oceans on Earth weight about 1.35 x 1018 metric tonnes (1.488 x 1018 US tons), which is the equivalent of 1.35 billion trillion kg, or 2976 trillion trillion pounds. This is just 1/4400 the total mass of the Earth, which means that while the oceans cover 71% of the Earth’s surface, they only account for 0.02% of our planet’s total mass.
Many theories about the origins of water on Earth attribute it to collisions with comets and asteroids. Credit: NASA/JPL/Caltech
Source of Earth’s Water:
The origin of water on the Earth’s surface, as well as the fact that it has more water than any other rocky planet in the Solar System, are two of long-standing mysteries concerning our planet. Not that long ago, it was believed that our planet formed dry some 4.6 billion years ago, with high-energy impacts creating a molten surface on the infant Earth.
According to this theory, water was brought to the world’s oceans thanks to icy comets, trans-Neptunian objects or water-rich meteoroids (protoplanets) from the outer reaches of the main asteroid belt colliding with the Earth.
However, more recent research conducted by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts, has pushed the date of these origins back further. According to this new study, the world’s oceans also date back 4.6 billion years, when all the worlds of the inner Solar System were still forming.
This conclusion was reached by examining meteorites thought to have formed at different times in the history of the Solar System. Carbonaceous chondrite, the oldest meteorites that have been dated to the very earliest days of the Solar System, were found to have the same chemistry as those originating from protoplanets like Vesta. This includes a significance presence of water.
These meteorites are dated to the same epoch in which water was believed to have formed on Earth – some 11 million years after the formation of the Solar System. In short, it now appears that meteorites were depositing water on Earth in its earliest days.
While not ruling out the possibility that some of the water that covers 71 percent of Earth today may have arrived later, these findings suggest that there was enough already here for life to have begun earlier than thought.
Artist view of an asteroid (with companion) passing near Earth. Credit: P. Carril / ESA
Asteroids and comets have a few things in common. They are both celestial bodies orbiting our Sun, and they both can have unusual orbits, sometimes straying close to Earth or the other planets. They are both “leftovers” — made from materials from the formation of our Solar System 4.5 billion years ago. But there are a few notable differences between these two objects, as well. The biggest difference between comets and asteroids, however, is what they are made of.
While asteroids consist of metals and rocky material, comets are made up of ice, dust, rocky materials and organic compounds. When comets get closer to the Sun, they lose material with each orbit because some of their ice melts and vaporizes. Asteroids typically remain solid, even when near the Sun.
Right now, the majority of asteroids reside in the asteroid belt, a region between the orbits of Mars and Jupiter which may hold millions of space rocks of varying sizes. On the other hand, the majority of comets are in the farthest reaches of our Solar System: either 1. in the Kuiper Belt — a region just outside the orbit of the dwarf planet Pluto that may have millions of icy comets (as well as many icy dwarf planets like Pluto and Eris); or 2. the Oort Cloud, a region where trillions of comets may circle the Sun at huge distances of up to 20 trillion kilometers (13 trillion miles).
Anillustration of what the Oort cloud might be like. Credit: Don Yeomans/JPL.
Some scientists think asteroids formed much closer to the Sun, where it was too warm for any ices to remain solid, while comets formed farther from the Sun and were therefore able to retain ice. However, other scientists think that the comets that are now in the Kuiper Belt and Oort cloud actually formed in the inner Solar System, but were then flung out from the gravitation effects of the giant planets Jupiter and Saturn.
We do know that gravitational perturbations periodically jar both asteroids and comets from their usual “homes” — setting them on orbital courses that bring them closer to the Sun, as well as Earth.
When comets approach the Sun, some of their ices melt. This causes another notable difference between asteroids and comets: comets have “tails” while asteroids generally don’t. When the ices in comets begin to melt and other materials vaporize from the heat from the Sun, this forms a glowing halo that extends outward from the comet as it sails through space. The ice and compounds like methane and ammonia develop a fuzzy, cloud-like shell called a coma. Forces exerted on the coma by the Sun’s radiation pressure and solar wind cause an enormous, elongated tail to form. Tails always points away from the Sun.
Asteroids typically don’t have tails, even those near the Sun. But recently, astronomers have seen some asteroids that have sprouted tails, such as asteroid P/2010 A2. This seems to happen when the asteroid has been hit or pummeled by other asteroids and dust or gas is ejected from their surfaces, creating a sporadic tail effect. These so-called “active asteroids” are a newly recognized phenomenon, and as of this writing, only 13 known active asteroids have been found in the main asteroid belt, and so they are very rare.
Another difference between asteroids and comets is in their orbital patterns. Asteroids tend to have shorter, more circular orbits. Comets tend to have very extended and elongated orbits, which often exceed 50,000 AU from the Sun. (*Note: 1 AU, or Astronomical Unit, equals the distance from the Earth to the Sun.) Some, called long-period comets come from the Oort Cloud and are in big elliptical orbits of the Sun that take them far out beyond the planets and back. Others, called short-period comets come from the Kuiper Belt and travel in shorter orbits around the Sun.
There is a big difference when it comes to numbers… although there is a caveat in that we don’t know precisely how many asteroids OR comets there are in our Solar System, since many have never been seen. Astronomers have discovered millions of asteroids – some as small as dust particles and others measuring hundreds of kilometers across. But as of this writing, astronomers have found only about 4,000 comets. However, some estimates say there could be one hundred billion comets in the Oort cloud.
The fact that asteroids and comets were both formed during the earliest days of our Solar System has scientists studying both with keen interest. By examining them up close with satellites and landers — such as the current Rosetta mission with the Philae lander to Comet 67P — scientists hope to learn more about what our Solar System looked like in its earliest days. The next mission to a comet will be the JAXA Hayabusa-2 mission, which should launch at the end of November or early December 2014, arriving in 2018 to asteroid (162173) 1999 JU. Here’s a list of past missions to asteroids and comets.
Scientists also study comets and asteroids to determine the likelihood of them hitting Earth and other planets, and what effect their flybys could have on planetary atmospheres. In November of 2014, a comet named Siding Spring flew very close to Mars, and scientists are still studying the encounter. But this may happen more often that we think: one recent study says that Mars gets bombarded by 200 small asteroids or comets every year.
How likely is it that our planet could be hit by a large asteroid or comet? We do know that Earth has been hit many times in the past by asteroids and comets whose orbits bring them into the inner Solar System. There is strong scientific evidence that cosmic collisions played a major role in the mass extinctions documented in Earth’s fossil records. These objects that come close to Earth, known as Near Earth Objects or NEOs, still pose a danger to Earth today. But NASA, ESA and other space agencies have search programs that have discovered hundreds of thousands of main-belt asteroids, comets. None at this time pose any threat to Earth. You can find out more on this topic at NASA’s Near Earth Object Program website.
Additionally, the possibility of mining both asteroids and comets someday is also becoming a source of interest for industrialists and commercial space ventures, such as Planetary Resources.
Not only will the Mars orbiters gather information about the comet and its dust before, during and after the encounter, a fleet of additional telescopes will make the most of the rare opportunity. Credit: NASA.
Comet Siding Spring will pass close to Mars today, Sunday, October 19, at 18:32 UTC. The comet will come within 139,500 km (87,000 miles) of the Red Planet, which is sixteen times closer to Mars than any known comet has ever come to Earth. About 100 minutes after the closest approach, the densest part of the comet’s tail will pass Mars’ location. You can watch live below courtesy of Slooh, ESA and the Virtual Telescope, below:
Slooh will feature two shows. The first show, billed “Close Call – Comet Siding Spring Zips by Mars,” will start at 11:15 AM PDT / 2:15 PM EDT / 18:15 UTC – International times here where Slooh will track Comet Siding Spring on close-approach live from South Africa and later from the Canary Islands. The second show, billed “Comet Siding Spring – the Outcome” will start at 5:30 PM PDT / 8:30 PM EDT / 00:30 UTC (10/20) – International times here – where Slooh will continue to track the comet live from Slooh’s southern observatory located at the Catholic University (PUC) – both shows will feature expert commentary by esteemed astrobiologist David Grinspoon and Slooh host Geoff Fox. The latter show will feature a special discussion with Slooh astronomer Bob Berman, who will be on location in Chile. Viewers can ask questions during each show by using hashtag #SloohComet.
