January 30, 2018January 30, 2018 by Fraser Cain

What’ll It Take to Find Life? Searching the Universe for Biosignatures

An artist's interpretation of HD 189733. It looks nice and blue, but it's actually a nightmare world that could be raining glass with 2 km/s winds. Credit: ESO/M. Kornmesser

The supertelescopes are coming, enormous ground and space-based observatories that’ll let us directly observe the atmospheres of distant worlds. We know there’s life on Earth, and our atmosphere tells the tale, so can we do the same thing with extrasolar planets? It turns out, coming up with a single biosignature, a chemical in the atmosphere that tells you that yes, absolutely, there’s life on that world, is really tough.

I’ve got to admit, I’ve been pretty bad for this in the past. In old episodes of Astronomy Cast and the Weekly Space Hangout, even here in the Guide to Space, I’ve said that if we could just sample the atmosphere of a distant world, we could say with conviction if there’s life there.

Just detect ozone in the atmosphere, or methane, or even pollution and you could say, “there’s life there.” Well, future Fraser is here to correct past Fraser. While I admire his naive enthusiasm for the search for aliens, it turns out, as always, things are going to be more difficult than we previously thought.

Astrobiologists are actually struggling to figure out a single smoking gun biosignature that could be used to say there’s life out there. And that’s because natural processes seem to have clever ways of fooling us.

What are some potential biosignatures, why are they problematic, and what will it take to get that confirmation?

Let’s start with a world close to home: Mars.

For almost two decades, astronomers have detected large clouds of methane in the atmosphere of Mars. Here on Earth, methane comes from living creatures, like bacteria and farting cows. Furthermore, methane is easily broken down by sunlight, which means that this isn’t ancient methane leftover from billions of years ago. Some process on Mars is constant replenishing it.

But what?

Well, in addition to life, methane can form naturally through volcanism, when rocks interact with heated water.

NASA tried to get to the bottom of this question with the Spirit and Opportunity rovers, and it was expected that Curiosity should have the tools on board to find the source of the methane.

Panoramic image of the Curiosity rover, from September 2016. The pale outline of Aeolis Mons can be seen in the distance. Credit: NASA/JPL-Caltech/MSSS

Over the course of several months, Curiosity did detect a boost of methane down there on the surface, but even that has led to a controversy. It turns out the rover itself was carrying methane, and could have contaminated the area around itself. Perhaps the methane it detected came from itself. It’s also possible that a rocky meteorite fell nearby and released some gas that contaminated the results.

The European Space Agency’s ExoMars mission arrived at Mars in October, 2016. Although the Schiaparelli Lander was destroyed, the Trace Gas Orbiter survived the journey and began mapping the atmosphere of Mars in great detail, searching for places that could be venting methane, and so far, we don’t have conclusive results.

In other words, we’ve got a fleet of orbiters and landers at Mars, equipped with instruments designed to sniff out the faintest whiff of methane on Mars.

Artist’s impression visualising the separation of the ExoMars entry, descent and landing demonstrator module, Schiaparelli, from the Trace Gas Orbiter (TGO). Credit: ESA

There’s some really intriguing hints about how the methane levels on Mars seem to rise and fall with the seasons, indicating life, but astrobiologists still don’t agree.

Extraordinary claims require extraordinary evidence and all that.

Some telescopes can already measure the atmospheres of planets orbiting other stars. For the last decade, NASA’s Spitzer Space Telescope has been mapping out the atmospheres of various worlds. For example, here’s a map of the hot jupiter HD 189733b

Spitzer temperature map of HD 189733b (NASA)

. The place sucks, but wow, to measure an atmosphere, of another planet, that’s pretty spectacular.

They perform this feat by measuring the chemicals of the star while the planet is passing in front of it, and then measure it when there’s no planet. That tells you what chemicals the planet is bringing to the party.

They also were able to measure the atmosphere of HAT-P-26b, which is a relatively small Neptune-sized world orbiting a nearby star, and were surprised to find water vapor in the atmosphere of the planet.

Does that mean there’s life? Wherever we find water on Earth we find life. Nope, you can totally get water without having life.

When it launches in 2019, NASA’s James Webb Space Telescope is going to take this atmospheric sensing to the next level, allowing astronomers to study the atmospheres of many more worlds with a much higher resolution.

Illustration showing the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Credits: NASA/JPL-Caltech

One of the first targets for Webb will be the TRAPPIST-1 system with its half-dozen planets orbiting in the habitable zone of a red dwarf star. Webb should be able to detect ozone, methane, and other potential biosignatures for life.

So what will it take to be able to view a distant world and know for sure there’s life there.

Astrobiologist John Lee Grenfell from the German Aerospace Centre recently created a report, going through all the exoplanetary biosignatures that could be out there, and reviewed them for how likely they were to be an indication of life on another world.

The first target will be molecular oxygen, or O2. You’re breathing it right now. Well, 21% of every breath, anyway. Oxygen will last in the atmosphere of another world for thousands of years without a source.

It’s produced here on Earth by photosynthesis, but if a world is being battered by its star, and losing atmosphere, then the hydrogen is blown off into space, and molecular oxygen can remain. In other words, you can’t be certain either way.

How about ozone, aka O3? O2 is converted into O3 through a chemical process in the atmosphere. It sounds like a good candidate, but the problem is that there are natural processes that can produce ozone too. There’s an ozone layer on Venus, one on Mars, and they’ve even been detected around icy moons in the Solar System.

There’s nitrous oxide, also known as laughing gas. It’s produced as an output by bacteria in the soil, and helps contribute to the Earth’s nitrogen cycle. And there’s good news, Earth seems to be the only world in the Solar System that has nitrous oxide in its atmosphere.

But scientists have also developed models for how this chemical could have been generated in the Earth’s early history when its sulfur-rich ocean interacted with nitrogen on the planet. In fact, both Venus and Mars could have gone through a similar cycle.

In other words, you might be seeing life, or you might be seeing a young planet.

Ligeia Mare, shown in here in data obtained by NASA’s Cassini spacecraft, is the second largest known body of liquid on Saturn’s moon Titan. It is filled with liquid hydrocarbons, such as ethane and methane, and is one of the many seas and lakes that bejewel Titan’s north polar region. Credit: NASA/JPL-Caltech/ASI/Cornell

Then there’s methane, the chemical we spent so much time talking about. And as I mentioned, there’s methane produced by life here on Earth, but it’s also on Mars, and there are liquid oceans of methane on Titan.

Astrobiologists have suggested other hydrocarbons, like ethane, isoprene, but these have their own problems too.

What about the pollutants emitted by advanced civilizations? Astrobiologists call these “technosignatures”, and they could include things like chlorofluorocarbons, or nuclear fallout. But again, these chemicals would be hard to detect light years away.

Astronomers have suggested that we should search for dead earths, just to set a baseline. These would be worlds located in the habitable zone, but clearly life never got going. Just rock, water and a non-biologically created atmosphere.

The problem is that we probably can’t even figure out a way to confirm that a world is dead either. The kinds of chemicals you’d expect to see in the atmosphere, like carbon dioxide could be absorbed by oceans, so you can’t even make a negative confirmation.

One method might not even involve scanning atmospheres at all. The vegetation here on Earth reflects back a very specific wavelength of light in the 700-750 nanometer region. Astrobiologists call this the “red edge”, because you’ll see a 5X increase in reflectivity compared to other surfaces.

Although we don’t have the telescopes to do this today, there are some really clever ideas, like looking at how the light from a planet reflects onto a nearby moon, and analyze that. Searching for exoplanet earthshine.

In fact, back in the Earth’s early history, it would have looked more purple because of Archaean bacteria.

There’s a whole fleet of spacecraft and ground observatories coming online that’ll help us push further into this question.

ESA’s Gaia mission is going to map and characterize 1% of the stars in the Milky Way, telling us what kinds of stars are out there, as well as detect thousands of planets for further observation.

A conceptual image of the Transiting Exoplanet Survey Satellite. Image Credit: MIT — A conceptual image of the Transiting Exoplanet Survey Satellite.
Image Credit: MIT

The Transiting Exoplanet Space Survey, or TESS, launches in 2018, and will find all the transiting Earth-sized and larger exoplanets in our neighborhood.

The PLATO 2 mission will find rocky worlds in the habitable zone, and James Webb will be able to study their atmospheres. We also talked about the massive LUVOIR telescope that could come online in the 2030s, and take these observations to the next level.

And there are many more space and ground-based observatories in the works.

As this next round of telescopes comes online, the ones capable of directly measuring the atmosphere of an Earth-sized world orbiting another star, astrobiologists are going to struggling to find a biosignature that provides a clear sign there’s life there.

Instead of certainty, it looks like we’re going to have the same struggle to make sense of what we’re seeing. Astronomers will be disagreeing with each other, developing new techniques and new instruments to answer unsolved questions.

It’s going to take a while, and the uncertainty is going to be tough to handle. But remember, this is probably the most important scientific question that anyone can ask: are we alone in the Universe?

The answer is worth waiting for.

Source: John Lee Grenfell: A Review of Exoplanetary Biosignatures.

Hat tip to Dr. Kimberly Cartier for directing me to this paper. Follow her work on EOS Magazine.

January 30, 2018January 30, 2018 by Matt Williams

The Brightest Star in the Sky, Sirius, was Hiding a Cluster of Stars. Found by Gaia

Obscured Sirius reveals Gaia 1 cluster. Credit and Copyright: H. Kaiser/ESA

In December of 2013, the European Space Agency’s Gaia mission took to space. Since that time, this space observatory has been studying a billion astronomical objects – including stars, planets, comets, asteroids and galaxies – for the sake of creating the most precise 3D space catalog ever made. By the time the mission wraps up (later this year, barring extensions), it is expected to reveal some truly amazing things about our Universe.

In fact, with the first release of its data, the Gaia probe revealed something that has gone completely unnoticed until now. While viewing Sirius, the brightest star in the night sky, Gaia revealed a stellar cluster that had previously been obscured by Sirius’ bright light. This cluster – now known as the Gaia 1 Cluster – is now available to the public thanks to a picture that was taken by an amateur astronomer from Germany.

Given its brightness and the fact that it is visible from just about anywhere on the planet, Sirius has been known since antiquity, and was featured prominently in the astrological and astronomical traditions of many cultures. To the ancient Egyptians, the star was used to keep track of time and agriculture, since its return to the sky was linked to the annual flooding of the Nile.

*Artist’s impression of a white dwarf star in orbit around Sirius (a main sequence white dwarf). Credit: NASA, ESA and G. Bacon (STScI)*

In Ancient Greek mythology, Sirius represented the eye of the Canis Major constellation. Along with Canis Minor, it formed the Great Dog that diligently followed Orion, the Hunter. In Chinese astronomy, the star is known as the star of the “celestial wolf” and lies in the Mansion of Jing. And when Ptolemy created his influential astronomical tract in the 3rd century CE (the Almagest), he used Sirius as the location for the globe’s central meridian.

By the mid-19th century, astronomers determined that Sirius is actually a binary star system. Essentially, the star system consists of a main sequence white dwarf that is roughly two Solar masses and a white dwarf that is slightly more massive than our Sun. Sirius’ bright appearance means that astronomers have had plenty of light to study the star’s properties, but also causes it to outshine other celestial objects in its vicinity.

However, in the course of counting the stars around Sirius, Gaia’s sophisticated instruments managed to detect the Gaia 1 Cluster for the first time. News of both this cluster and another newly-discovered one (the Gaia 2 Cluster) became public after the first release of Gaia data, which took place in September 2016. News of this discovery sent ripples through the astronomical community and has led to much research into this cluster and its companion.

News of the discovery also prompted attempts to visually capture the cluster. Roughly a year ago, Harald Kaiser – an amateur astronomer from Karlsruhe, Germany – attended a public talk about the Gaia mission, where he learned about the Gaia 1 Cluster being spotted near Sirius. Kaiser then eagerly waited for the next clear night so he could find the cluster himself using his 30 cm telescope.

*The ESA’s Gaia mission is currently on a five-year mission to map the stars of the Milky Way. Credit: ESA/ATG medialab; background: ESO/S. Brunier.*

After snapping a picture of Sirius and correcting for its bright glare, he was able to capture some of the brightest stars in the cluster. As you can see from the image he took (at top), the cluster lies slightly to the left of Sirius and shows a smattering of some of its largest and brightest stars. In addition to revealing the location of this cluster, Kaiser’s efforts are also part of a larger effort to capitalize on the Gaia mission’s progress.

According to a study released in February of last year – led by Sergey Kopsov of Carnegie Melon University – Gaia 1 is a particularly massive cluster. In essence, it weighs in at an impressive 22,000 Solar Masses, is about 29 light-years (9 parsecs) in diameter, and is located 15,000 light years (4.6 kiloparsecs) from Earth. In addition to its size and the fact that it was previously undiscovered, it’s proximity also makes it an opportune target for future research.

The announcement of this cluster has also caused a fair degree of excitement in the scientific community since it validates the capabilities of Gaia and serves as an example of the kinds of things it is expected to reveal. Astronomers are now looking forward to Gaia’s second data release (planned for April 25th) which is expected to provide even more possibilities for new and exciting discoveries.

And be sure to check out this video about the Gaia mission, courtesy of the ESA:

Further Reading: ESA

January 29, 2018 by Evan Gough

The Most Detailed Map Ever Made of the Milky Way in Radio Waves

The FUGIN project used the 45 meter Nobeyama radio telescope in Japan to produce the most detailed radio wave map yet of the Milky Way. Image: NAOJ/NASA/JPL-Caltech — The FUGIN project used the 45 meter Nobeyama radio telescope in Japan to produce the most detailed radio wave map yet of the Milky Way. Top: Three color (false color) radio map of the Milky Way (l=10-50 deg) obtained by the FUGIN Project. Red, green, and blue represent the radio intensities of 12CO, 13CO, and C18O, respectively. Second Line: Infrared image of the same region obtained by the Spitzer Space Telescope. Red, green, and blue represent the intensities of 24?m, 8?m, and 5.8?m radio waves respectively. Top Zoom-In: Three color radio map of the Milky Way (l=12-22 deg) obtained by the FUGIN Project. The colors are the same as the top image. Lower-Left Zoom-In: Enlarged view of the W51 region. The colors are the same as the top image.Lower-Right Zoom-In: Enlarged view of the M17 region. The colors are the same as the top image. Image: NAOJ/NASA/JPL-Caltech

A Japanese telescope has produced our most detailed radio wave image yet of the Milky Way galaxy. Over a 3-year time period, the Nobeyama 45 meter telescope observed the Milky Way for 1100 hours to produce the map. The image is part of a project called FUGIN (FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope.) The multi-institutional research group behind FUGIN explained the project in the Publications of the Astronomical Society of Japan and at arXiv.

The Nobeyama 45 meter telescope is located at the Nobeyama Radio Observatory, near Minamimaki, Japan. The telescope has been in operation there since 1982, and has made many contributions to millimeter-wave radio astronomy in its life. This map was made using the new FOREST receiver installed on the telescope.

When we look up at the Milky Way, an abundance of stars and gas and dust is visible. But there are also dark spots, which look like voids. But they’re not voids; they’re cold clouds of molecular gas that don’t emit visible light. To see what’s happening in these dark clouds requires radio telescopes like the Nobeyama.

The Nobeyama 45m radio telescope at the Nobeyama Radio Observatory in Japan. Image:NAOJ

The Nobeyama was the largest millimeter-wave radio telescope in the world when it began operation, and it has always had great resolution. But the new FOREST receiver has improved the telescope’s spatial resolution ten-fold. The increased power of the new receiver allowed astronomers to create this new map.

The new map covers an area of the night sky as wide as 520 full Moons. The detail of this new map will allow astronomers to study both large-scale and small-scale structures in new detail. FUGIN will provide new data on large structures like the spiral arms—and even the entire Milky Way itself—down to smaller structures like individual molecular cloud cores.

FUGIN is one of the legacy projects for the Nobeyama. These projects are designed to collect fundamental data for next-generation studies. To collect this data, FUGIN observed an area covering 130 square degrees, which is over 80% of the area between galactic latitudes -1 and +1 degrees and galactic longitudes from 10 to 50 degrees and from 198 to 236 degrees. Basically, the map tried to cover the 1st and 3rd quadrants of the galaxy, to capture the spiral arms, bar structure, and the molecular gas ring.

Starscape photograph taken at Nobeyama Radio Observatory by Norikazu Okabe. The FUGIN observation region (l=10-50 deg) is marked. Credit: National Astronomical Observatory of Japan

The aim of FUGIN is to investigate physical properties of diffuse and dense molecular gas in the galaxy. It does this by simultaneously gathering data on three carbon dioxide isotopes: 2CO, 13CO, and 18CO. Researchers were able to study the distribution and the motion of the gas, and also the physical characteristics like temperature and density. And the studying has already paid off.

FUGIN has already revealed things previously hidden. They include entangled filaments that weren’t obvious in previous surveys, as well as both wide-field and detailed structures of molecular clouds. Large scale kinematics of molecular gas such as spiral arms were also observed.

An artist’s image showing the major features of the Milky Way galaxy. Credit: NASA/JPL-Caltech, ESO, J. Hurt

But the main purpose is to provide a rich data-set for future work by other telescopes. These include other radio telescopes like ALMA, but also telescopes operating in the infrared and other wavelengths. This will begin once the FUGIN data is released in June, 2018.

Millimeter wave radio astronomy is powerful because it can “see” things in space that other telescopes can’t. It’s especially useful for studying the large, cold gas clouds where stars form. These clouds are as cold as -262C (-440F.) At temperatures that low, optical scopes can’t see them, unless a bright star is shining behind them.

Even at these extremely low temperatures, there are chemical reactions occurring. This produces molecules like carbon monoxide, which was a focus of the FUGIN project, but also others like formaldehyde, ethyl alcohol, and methyl alcohol. These molecules emit radio waves in the millimeter range, which radio telescopes like the Nobeyama can detect.

The top-level purpose of the FUGIN project, according to the team behind the project, is to “provide crucial information about the transition from atomic gas to molecular gas, formation of molecular clouds and dense gas, interaction between star-forming regions and interstellar gas, and so on. We will also investigate the variation of physical properties and internal structures of molecular clouds in various environments, such as arm/interarm and bar, and evolutionary stage, for example, measured by star-forming activity.”

This new map from the Nobeyama holds a lot of promise. A rich data-set like this will be an important piece of the galactic puzzle for years to come. The details revealed in the map will help astronomers tease out more detail on the structures of gas clouds, how they interact with other structures, and how stars form from these clouds.

January 29, 2018 by Matt Williams

Icy Worlds Like Europa and Enceladus Might Actually be too Soft to Land On

The moons of Europa and Enceladus, as imaged by the Galileo and Cassini spacecraft. Credit: NASA/ESA/JPL-Caltech/SETI Institute

Some truly interesting and ambitious missions have been proposed by NASA and other space agencies for the coming decades. Of these, perhaps the most ambitious include missions to explore the “Ocean Worlds” of the Solar System. Within these bodies, which include Jupiter’s moon Europa and Saturn’s moon Enceladus, scientists have theorized that life could exist in warm-water interior oceans.

By the 2020s and 2030s, robotic missions are expected to reach these worlds and set down on them, sampling ice and exploring their plumes for signs of biomarkers. But according to a new study by an international team of scientists, the surfaces of these moons may have extremely low-density surfaces. In other words, the surface ice of Europa and Enceladus could be too soft to land on.

The study, titled “Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations“, was recently published in the scientific journal Icarus. The study was led by Robert M.Nelson, the Senior Scientist at the Planetary Science Institute (PSI) and included members from NASA’s Jet Propulsion Laboratory, the California Polytechnic State University at Pomona, and multiple universities.

*Artist’s rendering of a possible Europa Lander mission, which would explore the surface of the icy moon in the coming decades. Credit: NASA/JPL-Caltech*

For the sake of their study, the team sought to explain the unusual negative polarization behavior at low phase angles that has been observed for decades when studying atmosphereless bodies. This polarization behavior is thought to be the result of extremely fine-grained bright particles. To simulate these surfaces, the team used thirteen samples of aluminum oxide powder (Al²O³).

Aluminum oxide is considered to be an excellent analog for regolith found on high aldebo Airless Solar System Bodies (ASSB), which include Europa and Encedalus as well as eucritic asteroids like 44 Nysa and 64 Angelina. The team then subjected these samples to photopolarimetric examinations using the goniometric photopolarimeter at Mt. San Antonio College.

What they found was that the bright grains that make up the surfaces of Europa and Enceladus would measure about a fraction of a micron and have a void space of about 95%. This corresponds to material that is less dense than freshly-fallen snow, which would seem to indicate that these moon’s have very soft surfaces. Naturally, this does not bode well for any missions that would attempt to set down on Europa or Enceladus’ surface.

But as Nelson explained in PSI press release, this is not necessarily bad news, and such fears have been raised before:

“Of course, before the landing of the Luna 2 robotic spacecraft in 1959, there was concern that the Moon might be covered in low density dust into which any future astronauts might sink. However, we must keep in mind that remote visible-wavelength observations of objects like Europa are only probing the outermost microns of the surface.”

*Enceladus in all its glory. NASA has announced that Enceladus, Saturn’s icy moon, has hydrogen in its oceans. Image: NASA/JPL/Space Science Institute*

So while Europa and Enceladus may have surfaces with a layer of low-density ice particles, it does not rule out that their outer shells are solid. In the end, landers may be forced to contend with nothing more than a thin sheet of snow when setting down on these worlds. What’s more, if these particles are the result of plume activity or action between the interior and the surface, they could hold the very biomarkers the probes are looking for.

Of course, further studies are needed before any robotic landers are sent to bodies like Europa and Enceladus. In the coming years, the James Webb Space Telescope will be conducting studies of these and other moons during its first five months in service. This will include producing maps of the Galilean Moons, revealing things about their thermal and atmospheric structure, and searching their surfaces for signs of plumes.

The data the JWST obtains with its advanced suite of spectroscopic and near-infrared instruments will also provide additional constraints on their surface conditions. And with other missions like the ESA’s proposed Europa Clipper conducting flybys of these moons, there’s no shortage to what we can learn from them.

Beyond being significant to any future missions to ASSBs, the results of this study are also likely to be of value when it comes to the field of terrestrial geo-engineering. Essentially, scientists have suggested that anthropogenic climate change could be mitigated by introducing aluminum oxide into the atmosphere, thus offsetting the radiation absorbed by greenhouse gas emissions in the upper atmosphere. By examining the properties of these grains, this study could help inform future attempts to mitigate climate change.

This study was made possible thanks in part to a contract provided by NASA’s Jet Propulsion Laboratory to the PSI. This contract was issued in support of the NASA Cassini Saturn Orbiter Visual and Infrared Mapping Spectrometer instrument team.

Further Reading: Planetary Science Institute, Icarus

January 29, 2018March 21, 2018 by Susie Murph

Astronomy Cast Ep. 476: The Overview Effect

After they’ve been to space, many astronauts report that seeing the world from above has given them a totally new perspective on humanity and the state of our planet. It’s called the Overview Effect. Today we’ll talk about this, and what this perspective can teach us all.

We usually record Astronomy Cast every Friday at 3:00 pm EST / 12:00 pm PST / 20:00 PM UTC. You can watch us live on AstronomyCast.com, or the AstronomyCast YouTube page.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

If you would like to support Astronomy Cast, please visit our page at Patreon here – https://www.patreon.com/astronomycast. We greatly appreciate your support!

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

January 26, 2018 by Evan Gough

NASA’s Insight Lander Spreads Its Solar Wings. It’ll Fly To Mars In May, 2018

The Insight lander responds to commands to spread its solar arrays during a January 23, 2018 test at the Lockheed Martin clean room in Littleton, Colorado. Image: Lockheed Martin Space

May 2018 is the launch window for NASA’s next mission to Mars, the InSight Lander. InSight is the next member of what could be called a fleet of human vehicles destined for Mars. But rather than working on the question of Martian habitability or suitability for life, InSight will try to understand the deeper structure of Mars.

InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport. InSight will be the first robotic explorer to visit Mars and study the red planet’s deep interior. The work InSight does should answer questions about the formation of Mars, and those answers may apply to the history of the other rocky planets in the Solar System. The lander, (InSight is not a rover) will also measure meteorite impacts and tectonic activity happening on Mars currently.

This video helps explain why Mars is a good candidate to answer questions about how all our rocky planets formed, not just Mars itself.

InSight was conceived as part of NASA’s Discovery Program, which are missions focused on important questions all related to the “content, origin, and evolution of the solar system and the potential for life elsewhere”, according to NASA. Understanding how our Solar System and its planets formed is a key part of the Discovery Program, and is the question InSight was built to answer.

This artist's illustration of InSight on a photo background of Mars shows the lander fully deployed. The solar arrays are open, and in the foreground two of its instruments are shown. On the left is the SEIS instrument, and on the right is the HP3 probe. Image: NASA/Lockheed Martin — This artist’s illustration of InSight on a photo background of Mars shows the lander fully deployed. The solar arrays are open, and in the foreground two of its instruments are shown. On the left is the SEIS instrument, and on the right is the HP3 probe. Image: NASA/Lockheed Martin

To do its work, InSight will deploy three instruments: SEIS, HP³, and RISE.

SEIS

This is InSight’s seismic instrument, designed to take the Martian pulse. It stands for Seismic Experiment for Internal Structure.

SEIS sits patiently under its dome, which protects it from Martian wind and thermal effects, and waits for something to happen. What’s it waiting for? For seismic waves caused by Marsquakes, meteorite impacts, or by the churning of magma deep in the Martian interior. These waves will help scientists understand the nature of the material that first formed Mars and the other rocky planets.

HP³

HP³ is InSight’s heat probe. It stands for Heat Flow and Physical Properties Probe. Upon deployment on the Martian surface, HP³ will burrow 5 meters (16 ft.) into Mars. No other instrument has ever pierced Mars this deeply. Once there, it will measure the heat flowing deeply within Mars.

In this image, the Heat Flow and Physical Properties Probe is shown inserted into Mars. Image: NASA

Scientists hope that the heat measured by HP³ will help them understand whether or not Mars formed from the same material that Earth and the Moon formed from. It should also help them understand how Mars evolved after it was formed.

RISE

RISE stands for Rotation and Interior Structure Experiment. RISE will measure the Martian wobble as it orbits the Sun, by precisely tracking InSight’s position on the surface. This will tell scientists a lot about the deep inner core of Mars. The idea is to determine the depth at which the Martian core is solid. It will also tell us which elements are present in the core. Basically, RISE will tell us how Mars responds to the Sun’s gravity as it orbits the Sun. RISE consists of two antennae on top of InSight.

InSight will land at Elysium Planitia which is a flat and smooth plain just north of the Martian equator. This is considered a perfect location or InSight to study the Martian interior. The landing sight is not far from where Curiosity landed at Gale Crater in 2012.

InSight will land at Elysium Planitia, just north of the Martian equator. Image: NASA/JPL-CalTech

InSight will be launched to Mars from Vandenberg Air Force Base in California by an Atlas V-401 rocket. The trip to Mars will take about 6 months. Once on the Martian surface, InSight’s mission will have a duration of about 728 Earth days, or just over 1 Martian year.

InSight won’t be launching alone. The Atlas that launches the lander will also launch another NASA technology experiment. MarCO, or Mars Cube One, is two suitcase-size CubeSats that will travel to Mars behind InSight. Once in orbit around Mars, their job is to relay InSight data as the lander enters the Martian atmosphere and lands. This will be the first time that miniaturized CubeSat technology will be tested at another planet.

One of the MarCO Cubesats that will be launched with InSight. This will be the first time that CubeSat technology will be tested at another planet. Image: NASA/JPL-CalTech

If the MarCO experiment is successful, it could be a new way of relaying mission data to Earth. MarCO will relay news of a successful landing, or of any problems, much sooner. However, the success of the InSight lander is not dependent on a successful MarCO experiment.

January 26, 2018 by David Dickinson

Get Set For a “Super Blue Blood Moon Total Lunar Eclipse”

Can you feel the tremor in the Force? Early next Wednesday morning internet astro-memes collide, in one of the big ticket sky events of the year, with a total lunar eclipse dubbed as — get ready — a Super Blue Blood Moon total lunar eclipse.

Specifics on the eclipse: That’s a mouthful, for sure. This is the first eclipse of 2018, and only one of two featuring totality, lunar or solar. Wednesday morning’s eclipse favors the region centered on the Pacific Rim, with regions of Asia and Australia seeing the evening eclipse at moonrise, while most of North America will see totality early Wednesday morning at moonset. Only the regions of the Canadian Maritimes and the United States east of the Mississippi misses out on the spectacle’s climax, catching a partially eclipsed Moon setting in the west at sunrise.

2018 features four eclipses overall, two lunar and two solar. Paired with this eclipse is a partial solar eclipse on February 15^th favoring the very southern tip of South America, followed by another total lunar eclipse this summer on July 27^th. The final eclipse for 2018 is a partial solar eclipse on August 11^th, favoring northern Europe and northeastern Asia.

What’s all the fuss about? Let’s dissect the eclipse, meme by meme:

Why it’s Super: Totality for this eclipse lasts 1 hour, 16 minutes and 4 seconds, the longest since April 15^th, 2014. Full Moon (and maximum duration for this eclipse) occurs at 13:30 Universal Time (UT), just 27 hours after the Moon reaches perigee the day prior on January 30^th at 9:55 UT . Note that this isn’t quite the closest perigee of the year in space and time: the January 1^st Full Moon perigee beat it out for that title by 2,429 km (1509 miles) and 23 hours.

Worldwide circumstances for Wednesday’s super blue blood moon total lunar eclipse. NASA

Why it’s Blue: This is the second Full Moon of the month, making this month’s Moon “Blue” in the modern sense of the term. This definition comes down to us thanks to a misinterpretation in the July 1943 issue of Sky & Telescope. The Maine Farmer’s Almanac once used an even more convoluted definition of a Blue Moon as “the third Full Moon in an astronomical season with four,” and legend has it, used blue ink in the almanac printing to denote that extra spurious Moon… anyone have any old Maine Farmer’s Almanacs in the attic to verify the tale?

Note that Blue Moons aren’t all that rare… the month of March 2018 also hosts two Full Moons, while truncated February 2018 contains none, sometimes referred to as a “Black Moon”.

Why All the Blood: The cone of the Earth’s umbra or dark inner shadow isn’t completely devoid of light. Instead, you’re seeing sunlight from all the Earth’s sunrises and sunsets around its limb, filtered into the shadow of the the planet onto the nearside of the Moon. Standing on the Earthward facing side of the Moon, you would witness a solar eclipse as the Earth passed between the Moon and the Sun. Unlike the neat near fit for solar eclipses on the Earth, however, solar eclipses on the Moon can last over an hour, as the Earth appears about three times larger than the disk of the Sun. And although astronauts have witnessed eclipses from space, no human has yet stood on the Moon and witnessed the ring of fire surrounding the Earth during a solar eclipse.

Tales of the Saros: For saros buffs, this eclipse is member 49 of 74 lunar eclipses for lunar saros cycle 124, stretching all the way back to August 17^th, 1152. If you caught the total lunar eclipse on January 21^st, 2000, you saw the last eclipse in this cycle. Stick around until April 18^th, 2144 AD and you can watch the final total lunar eclipse for saros 124.

Unlike total solar eclipses, lunar eclipses are leisurely affairs. The entire penumbral phase of the eclipse lasts for over 5 hours, though you probably won’t notice the subtle shading on the limb of the Moon until its about halfway immersed in the Earth’s penumbral shadow.

Not all total lunar eclipses are the same. Depending on how deep the Moon passes through the Earth’s shadow and the murkiness of the Earth’s atmosphere, the Moon can appear anywhere from a sickly orange, to a deep brick red during totality… for example, the Moon almost disappeared entirely during a total lunar eclipse shortly after the eruption of Mount Pinatubo in the early 1990s!

The color of the Moon during totality is known as its Danjon Number, with 4 being bright with a bluish cast on the outer limb of the Moon, and 0 appearing dark and deep red.

This is also one of the only times you can see that the Earth is indeed round with your own eyes as the curve of the shadow cast by our homeworld falls back across the Moon. This curve is the same, regardless of the angle, and whether the Moon is high above near the zenith, or close to the horizon.

Don’t miss the first eclipse of 2018 and the (deep breath) super blue blood Moon total lunar eclipse!

-Clouded out, or on the wrong side of the planet? Watch the January 31st eclipse live courtesy of the Virtual Telescope Project.

January 25, 2018January 25, 2018 by Matt Williams

The New Earth-Sized Planet Hunting Telescope ExTrA is Now Online

The ExTrA telescopes are sited at ESO’s La Silla Observatory in Chile. They will be used to search for and study Earth-sized planets orbiting nearby red dwarf stars. Credit: ESO/Emmanuela Rimbaud

Ever since the Kepler space telescope began discovering thousands of exoplanets in our galaxy, astronomers have been eagerly awaiting the day when next-generation missions are deployed. These include the much-anticipated James Webb Space Telescope, which is scheduled to take to space in 2019, but also the many ground-based observatories that are currently being constructed.

One of these is the Exoplanets in Transits and their Atmospheres (ExTrA) project, which is the latest addition to the ESO’s La Silla Observatory in Chile. Using the Transit Method, this facility will rely on three 60-centimeter (23.6 in) telescopes to search for Earth-sized exoplanets around M-type (red dwarf) stars in the Milky Way Galaxy. This week, the facility began by collecting its first light.

The Transit Method (aka. Transit Photometry) consists of monitoring stars for periodic dips in brightness. These dips are caused by planets passing in front of the star (aka. transiting) relative to the observer. In the past, detecting planets around M-type stars using this method has been challenging since red dwarfs are the smallest and dimmest class of star in the known Universe and emit the majority of their light in the near-infrared band.

*Artist’s impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).*

However, these stars have also proven to be treasure trove when it comes to rocky, Earth-like exoplanets. In recent years, rocky planets have been discovered around star’s like Proxima Centauri and Ross 128, while TRAPPIST-1 had a system of seven rocky planets. In addition, there have been studies that have indicated that potentially-habitable, rocky planets could be very common around red dwarf stars.

Unlike other facilities, the ExTrA project is well-suited to conduct surveys for planets around red dwrfs because of its location on the outskirts of the Atacama Desert in Chile. As Xavier Bonfils, the project’s lead researcher, explained:

“La Silla was selected as the home of the telescopes because of the site’s excellent atmospheric conditions. The kind of light we are observing – near-infrared – is very easily absorbed by Earth’s atmosphere, so we required the driest and darkest conditions possible. La Silla is a perfect match to our specifications.”

In addition, the ExTrA facility will rely on a novel approach that involves combining optical photometry with spectroscopic information. This consists of its three telescopes collecting light from a target star and four companion stars for comparison. This light is then fed through optical fibers into a multi-object spectrograph in order to analyze it in many different wavelengths.

*The ExTrA telescopes are sited at ESO’s La Silla Observatory in Chile. Credit: ESO/Petr Horálek*

This approach increases the level of achievable precision and helps mitigate the disruptive effect of Earth’s atmosphere, as well as the potential for error introduced by instruments and detectors. Beyond the goal of simply finding planets transiting in front of their red dwarf stars, the ExTrA telescopes will also study the planets it finds in order to determine their compositions and their atmospheres.

In short, it will help determine whether or not these planets could truly be habitable. As Jose-Manuel Almenara, a member of the ExTrA team, explained:

“With ExTrA, we can also address some fundamental questions about planets in our galaxy. We hope to explore how common these planets are, the behaviour of multi-planet systems, and the sorts of environments that lead to their formation,”

The potential to search for extra-solar planets around red dwarf stars is an immense opportunity for astronomers. Not only are they the most common star in the Universe, accounting for 70% of stars in our galaxy alone, they are also very long-lived. Whereas stars like our Sun have a lifespan of about 10 billion years, red dwarfs are capable of remaining in their main sequence phase for up to 10 trillion years.

*Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser*

For these reasons, there are those who think that M-type stars are our best bet for finding habitable planets in the long run. At the same time, there are unresolved questions about whether or not planets that orbit red dwarf stars can stay habitable for long, owing to their variability and tendency to flare up. But with ExTrA and other next-generation instruments entering into service, astronomers may be able to address these burning questions.

As Bonfils excitedly put it:

“With the next generation of telescopes, such as ESO’s Extremely Large Telescope, we may be able to study the atmospheres of exoplanets found by ExTra to try to assess the viability of these worlds to support life as we know it. The study of exoplanets is bringing what was once science fiction into the world of science fact.”

ExTrA is a French project funded by the European Research Council and the French Agence National de la Recherche and its telescopes will be operated remotely from Grenoble, France. Also, be sure to enjoy this video of the ExTrA going online, courtesy of the ESOcast:

Further Reading: ESO

January 25, 2018 by Evan Gough

Where’s the Line Between Massive Planet and Brown Dwarf Star?

This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026, observed by NASA's Hubble and Spitzer space telescopes. Brown dwarfs are more massive and hotter than planets but lack the mass required to become stars. Image credit: NASA

When is a Brown Dwarf star not a star at all, but only a mere Gas Giant? And when is a Gas Giant not a planet, but a celestial object more akin to a Brown Dwarf? These questions have bugged astronomers for years, and they go to the heart of a new definition for the large celestial bodies that populate solar systems.

An astronomer at Johns Hopkins University thinks he has a better way of classifying these objects, and it’s not based only on mass, but on the company the objects keep, and how the objects formed. In a paper published in the Astrophysical Journal, Kevin Schlaufman made his case for a new system of classification that could helps us all get past some of the arguments about which object is a gas giant planet or a brown dwarf. Mass is the easy-to-understand part of this new definition, but it’s not the only factor. How the object formed is also key.

In general, the less massive a star, the cooler it is. Though stars smaller than our Sun can still sustain heat-producing fusion reactions, protostars that are too small cannot. These “failed” stars are commonly known as brown dwarfs, and a new definition puts their range from between 10-75 times the mass of Jupiter. This artist’s concept compares the size of a brown dwarf to that of Earth, Jupiter, a low-mass star, and the Sun. (Credit: NASA/JPL-Caltech/UCB).

Schlaufman is an assistant professor in the Johns Hopkins Department of Physics and Astronomy. He has set a limit for what we should call a planet, and that limit is between 4 and 10 times the mass of our Solar System’s biggest planet, Jupiter. Above that, you’ve got yourself a Brown Dwarf star. (Brown Dwarfs are also called sub-stellar objects, or failed stars, because they never grew massive enough to become stars.)

“An upper boundary on the masses of planets is one of the most prominent details that was missing.” – Kevin Schlaufman, Johns Hopkins University, Dept. of Physics and Astronomy.

Improvements in observing other solar systems have led to this new definition. Where previously we only had our own Solar System as reference, we now can observe other solar systems with increasing effectiveness. Schlaufman observed 146 solar systems, and that allowed him to fill in some of the blanks in our understanding of brown dwarf and planet formation.

An image of Jupiter showing its storm systems. According to a new definition, Jupiter would be considered a brown dwarf if it had grown to over 10 times its mass when it was formed. Image: Gemini

“While we think we know how planets form in a big picture sense, there’s still a lot of detail we need to fill in,” Schlaufman said. “An upper boundary on the masses of planets is one of the most prominent details that was missing.”

Let’s back up a bit and look at how Brown Dwarfs and Gas Giants are related.

Solar systems are formed from clouds of gas and dust. In the early days of a solar system, one or more stars are formed out of this cloud by gravitational collapse. They ignite with fusion and become the stars we see everywhere in the Universe. The leftover gas and dust forms into planets, or brown dwarfs. This is a simplified version of solar system formation, but it serves our purposes.

In our own Solar System, only a single star formed: the Sun. The gas giants Jupiter and Saturn gobbled up most of the rest of the material. Jupiter gobbled up the lion’s share, making it the largest planet. But what if conditions had been different and Jupiter had kept growing? According to Schlaufman, if it had kept growing to over 10 times the size it is now, it would have become a brown dwarf. But that’s not where the new definition ends.

Metallicity and Chemical Makeup

Mass is only part of it. What’s really behind his new classification is the way in which the object formed. This involves the concept of metallicity in stars.

Stars have a metallicity content. In astrophysics, this means the fraction of a star’s mass that is not hydrogen or helium. So any element from lithium on down is considered a metal. These metals are what rocky planets form from. The early Universe had only hydrogen and helium, and almost insignificant amounts of the next two elements, lithium and beryllium. So the first stars had no metallicity, or almost none.

This is an image of M80, an ancient globular cluster of stars. Since these stars formed in the early universe, their metallicity content is very low. This means that gas giants like Jupiter would be rare or non-existent here, while brown dwarfs are likely plentiful. Image: By NASA, The Hubble Heritage Team, STScI, AURA - Great Images in NASA Description, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6449278 — This is an image of M80, an ancient globular cluster of stars. Since these stars formed in the early universe, their metallicity content is very low. This means that gas giants like Jupiter would be rare or non-existent here, while brown dwarfs are likely plentiful. Image: By NASA, The Hubble Heritage Team, STScI, AURA – Great Images in NASA Description, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6449278

But now, 13.5 billion years after the Big Bang, younger stars like our Sun have more metal in them. That’s because generations of stars have lived and died, and created the metals taken up in subsequent star formation. Our own Sun was formed about 5 billion years ago, and it has the metallicity we expect from a star with its birthdate. It’s still overwhelmingly made of hydrogen and helium, but about 2% of its mass is made of other elements, mostly oxygen, carbon, neon, and iron.

This is where Schlaufman’s study comes in. According to him, we can distinguish between gas giants like Jupiter, and brown dwarfs, by the nature of the star they orbit. The types of planets that form around stars mirror the metallicity of the star itself. Gas giants like Jupiter are usually found orbiting stars with metallicity equal to or greater than our Sun. But brown dwarfs aren’t picky; they form around almost any star. Why?

Brown Dwarfs and Planets Form Differently

Planets like Jupiter are formed by accretion. A rocky core forms, then gas collects around it. Once the process is done, you have a gas giant. For this to happen, you need metals. If metals are present for these rocky cores to form, their presence will be reflected in the metallicity of the host star.

But brown dwarfs aren’t formed by accretion like planets are. They’re formed the same way stars are; by gravitational collapse. They don’t form from an initial rocky core, so metallicity isn’t a factor.

This brings us back to Kevin Schlaufman’s study. He wanted to find out the mass at which point an object doesn’t care about the metallicity of the star they orbit. He concluded that objects above 10 times the mass of Jupiter don’t care if the star has rocky elements, because they don’t form from rocky cores. Hence, they’re not planets akin to Jupiter; they’re brown dwarfs that formed by gravitational collapse.

What Does It Matter What We Call Them?

Let’s look at the Pluto controversy to understand why names are important.

The struggle to accurately classify all the objects we see out there in space is ongoing. Who can forget the plight of poor Pluto? In 2006, the International Astronomical Union (IAU) demoted Pluto, and stripped it of its long-standing status as a planet. Why?

Because the new definition of what a planet is relied on these three criteria:

a planet is in orbit around a star.
a planet must have sufficient mass to assume a hydrostatic equilibrium (a nearly round shape.)
a planet has cleared the neighbourhood around its orbit

The more we looked at Pluto with better telescopes, the more we realized that it did not meet the third criteria, so it was demoted to Dwarf Planet. Sorry Pluto.

Pluto was re-classified as a dwarf planet based on our growing understanding of its nature. Will Schlaufman's new study help us more accurately classify gas giants and brown dwarfs? NASA's New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015. Credit: NASA/JHUAPL/SwRI — Pluto was re-classified as a dwarf planet based on our growing understanding of its nature. Will Schlaufman’s new study help us more accurately classify gas giants and brown dwarfs? NASA’s New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015. Credit: NASA/JHUAPL/SwRI

Our naming conventions for astronomical objects are important, because they help people understand how everything fits together. But sometimes the debate over names can get tiresome. (The Pluto debate is starting to wear out its welcome, which is why some suggest we just call them all “worlds.”)

Though the Pluto debate is getting tiresome, it’s still important. We need some way of understanding what makes objects different, and names that reflect that difference. And the names have to reflect something fundamental about the objects in question. Should Pluto really be considered the same type of object as Jupiter? Are both really planets in the same sense? The IAU says no.

The same principle holds true with brown dwarfs and gas giants. Giving them names based solely on their mass doesn’t really tell us much. Schlaufman aims to change that.

His new definition makes sense because it relies on how and where these objects form, not simply their size. But not everyone will agree, of course.

Let the debate begin.

January 25, 2018October 16, 2018 by Matt Williams

Perhaps the Best Part of Electron’s Successful Launch was its Payload: the Humanity Star

Peter Beck, founder of Rocket Lab, is shown with the Humanity Star. Credit: Rocket Lab

This past weekend, the New Zealand-based aerospace company Rocket Lab reached another milestone. On Sunday, January 21st, the company conducted the second launch – the first having taken place this past summer – of its Electron booster. This two-stage, lightweight rocket is central to the company’s vision of reducing the costs of individual launches by sending light payloads to orbit with regular frequency.

This mission was also important because it was the first time that the company sent payloads into orbit. In addition to several commercial payloads, the launch also sent a secret payload into orbit at the behest of the company’s founder (Peter Beck). It is known as the “Humanity Star“, a disco-like geodesic sphere that measures 1 meter (3.3 ft) in diameter and will form a bright spot in the sky that will be visible to people on Earth.

The Humanity Star is central to Beck’s vision of how space travel can improve the lives of people here on Earth. In addition to presenting extensive opportunities for scientific research, there is also the way it fosters a sense of unity between people and nations. This is certainly a defining feature of the modern space age, where cooperation has replaced competition as the main driving force.

*The Electron rocket prepping for its second launch last weekend. Credit: Rocket Lab*

As Beck explained to ArsTechnica in an interview before the launch:

“The whole point of the program is to get everybody looking up at the star, but also past the star into the Universe, and reflect about the fact that we’re one species, on one planet. This is not necessarily part of the Rocket Lab program; it’s more of a personal program. It’s certainly consistent with our goal of trying to democratize space.”

Like the Electron rocket, the Humanity Sphere is made of carbon fiber materials and it’s surface consists of 65 highly-reflective panels. Once it reaches an orbit of 300 by 500 km (186 by 310 mi), it will spend the next nine months there reflecting the light of the Sun back to Earth. Whether or not it will be visible to the naked eye remains to be seen, but Rocket Lab is confident it will be.

According to Beck, the sphere will be more visible than a Iridium flare, which are easily spotted from the surface. These flares occur when the solar panels or antennae of an Iridium satellite reflect sunlight in orbit. “Most people will be familiar with the Iridium flares, and this has got much, much more surface area than an Iridium flare,” Beck said. “In theory, it will be easy to find.”

*The payload will last for about nine months in orbit. Credit: Rocket Lab*

Beck got the idea for the project from talking to people about where they live. In his experience, people tend to think of their locality or nationality when they think of home. Whereas many people he had spoken to were aware that they lived on planet Earth, they were oblivious to where the Earth resided in the Solar System or the Universe at large. In this respect, the Humanity Sphere is meant to encourage people to look and think beyond.

As he states on the website the company created for the Humanity Sphere:

“For millennia, humans have focused on their terrestrial lives and issues. Seldom do we as a species stop, look to the stars and realize our position in the universe as an achingly tiny speck of dust in the grandness of it all.

“Humanity is finite, and we won’t be here forever. Yet in the face of this almost inconceivable insignificance, humanity is capable of great and kind things when we recognize we are one species, responsible for the care of each other, and our planet, together. The Humanity Star is to remind us of this.

“No matter where you are in the world, rich or in poverty, in conflict or at peace, everyone will be able to see the bright, blinking Humanity Star orbiting Earth in the night sky. My hope is that everyone looking up at the Humanity Star will look past it to the expanse of the universe, feel a connection to our place in it and think a little differently about their lives, actions and what is important.

“Wait for when the Humanity Star is overhead and take your loved ones outside to look up and reflect. You may just feel a connection to the more than seven billion other people on this planet we share this ride with.”

*The Electron rocket launching on Sunday afternoon, 2:42pm, New Zealand time. Credit: Rocket Lab*

The Humanity Star can also be tracked via the website. As of the penning of this article, it is moving south of the equator and should be visible to those living along the west coast of South America. So if you live in Colombia, Peru or Chile, look to the western skies and see if you can’t spot this moving star. After passing south over Antarctica, it will reemerge in the night skies over Central Asia.

Without a doubt, the Humanity Sphere is an inspired creation, and one which is in good company. Who can forget the “Blue Marble” picture snapped by the Apollo 17 astronauts, or Voyager 1‘s “pale blue dot” photo? And even for those who are too young to have witnessed it, the images of Neil Armstrong and Buzz Aldrin setting foot on the Moon still serve to remind us of how far we’ve come, and how much still awaits us out there.

Further Reading: ArsTechnica

Universe Today

Posts