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ATLANTIC SKIES: How big is the universe? – TheChronicleHerald.ca

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The joy of my life, my granddaughter Scarlet, asked me the other day, “Poppy, how big is the universe?”

Her boundless curiosity never ceases to amaze me. I attempted to explain to her, as best I could to an eight-year-old who has never travelled further than Halifax, N.S., that the universe, as we currently understand it, is very large – so large, in fact, that we have to measure it, not in terms of kilometers, but, rather, in light-years. Even then, the numbers are extremely big.

I am not sure my explanation of exactly what a light-year is (how far light travels through space in the course of one year, or approximately 9.5 trillion kilometers), and, how when multiplied by how far (in light-years) we can see out into space, did much to answer her initial query, as the resulting silence and quizzical expression on her face told me she couldn’t really grasp such distances (who can blame her?).

Her response just about summed up what, I imagine, most people would say: “Guess that really is pretty big, isn’t it, Poppy?”

“Yes, my darling, it certainly is,” I replied.

In the 1920s, the American astronomer, Edwin Hubble (after whom the Hubble Space Telescope is named) and his assistant, Milton Humason, proved that the galaxies they were studying and photographing were, in fact, moving outward as viewed from Earth, or receding, into deep space, and further, that the more distant the galaxy, the faster it was receding. This became known as Hubble’s Law.

Hubble’s discovery actually grew out of earlier work by Albert Einstein, who, in 1917, predicted that the universe was expanding, because space itself was expanding. Although, at the time, Einstein wasn’t confident enough in his expanding universe theory to publish it, it later formed the basis for his famous General Theory of Relativity.

When I use the term “universe” here, I mean the observable universe, the farthest point that we can see out into space with our best astronomical telescope – the Hubble Space Telescope (HST). In 2016, the HST photographed what, to date, is the most distant object – the galaxy GN-z11. Taking the expansion of the universe into consideration, it is approximately 32 billion light-years, or approximately 3.04 sextillion (3.04 followed by 21 zeros) kilometers away; a truly mind-boggling distance.

However, astronomers theorize that the actual universe is much, much larger. Starting at the moment of the universe’s theoretical creation (called the “Big Bang”, though not an actual explosion), the accepted age of the universe is now thought to be approximately 13.8 billion years. As the universe continues to expand, the most distant point in space from which we will ultimately receive light back from distant galaxies (which are increasingly moving away from us), known as the “cosmic horizon”, is estimated to be about 46 billion light-years away.

It is theorized that, due to the increasingly rapid rate of expansion of the universe as a whole, we will never see any light from objects beyond the cosmic horizon. However, when the James Webb telescope (a much larger and more sophisticated telescope than the HST) is launched on Oct. 31, 2021, the boundaries of the known universe will, undoubtedly, be extended.

Though the above distance figures are truly mind-blowing. and may make you feel incredibly small, it should, at the very least, underscore just how unique our life-bearing planet Earth is in the great infinite vastness of the cosmos and how wonderfully precious it is to have children and grandchildren who challenge you to think about it.

This week’s sky

Mercury remains too close to the sun to be visible this coming week. Venus (magnitude -4.2) is visible, as it has been these past few weeks, in the pre-dawn sky. It rises around 2:45 a.m., reaching its highest point at 34 degrees above the eastern horizon, before fading from sight as dawn breaks around 6:15 a.m.

Mars (magnitude -1.8) is visible in the early morning sky, rising in the east around 10:30 p.m., and achieving its highest altitude (50 degrees) above the southern horizon by about 4:20 a.m., before becoming lost in the dawn twilight by 6:15 a.m.

Jupiter and Saturn remain early evening objects, both visible side-by-side (bright Jupiter to the right) above the southeast horizon by about 8:30 p.m. Jupiter (magnitude -2.58) disappears from view around 12:40 a.m., when it sinks below seven degrees above the southeast horizon, followed by Saturn (magnitude +0.31) around 1:30 a.m., when it sinks below 10 degrees above the southwest horizon.

When the full moon closest to the Autumnal Equinox (Sept. 22), occurs in October, as it does this year on Oct. 1, it is known as the “Harvest Moon”. September’s Full Moon (Sept. 2) is referred to as the “Corn Moon,” the name given to it by Native American tribes, as this was when they usually harvested their corn crops.

Until next week, clear skies.

Events:

  • Sept. 2 – Full (corn) moon
  • Sept. 6 – Moon at apogee (farthest from Earth)

Glenn K. Roberts lives in Stratford, P.E.I., and has been an avid amateur astronomer since he was a small child. He welcomes comments from readers at glennkroberts@gmail.com.

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‘Extreme planet’ orbits star in three Earth days, has temperatures of 3120 degrees Celsius

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TORONTO —
Research on data from a new satellite is revealing strange new details about one of the “most extreme planets” in our known universe, and the blue, oddly-shaped star it orbits.

WASP-189b is 322 light years away from Earth in the constellation of Libra, has a permanent dayside and night side, and takes less than three Earth days to fully orbit its star — far faster than our 365 days.

“It is 20 times closer to [its star] than Earth is to the Sun,” Monika Lendl, lead author of the study from the University of Geneva, said in a press release.

WASP-189b is a gas giant, but it’s not any old gas giant. It is around one and a half times as large as Jupiter, and is part of a group called “ultra-hot Jupiters,” which are gas giants that are much larger and hotter than any planet we see in our solar system.

And this planet is even hotter than most other ultra-hot exoplanets scientists have identified. A paper published in the Astronomy & Astrophysics journal last week which detailed the new research described WASP-189b as “one of the most highly irradiated planets known thus far.”

It not only orbits incredibly close to its star, but the star itself, known as HD 133112, is one of the hottest stars we know of that has its own planetary system, at around 2,200 degrees Celsuis hotter than our Sun.

“Because it is so hot, the star appears blue and not yellow-white like the sun,” Willy Benz, professor of astrophysics at the University of Bern and head of the CHEOPS consortium, said in the release.

The dayside of the WASP-189b — the side that faces the star — is roughly 3,400 Kelvin, which is more than 3,120 degrees Celsius. It’s so hot that if there were iron present in the planet’s makeup, it would be gaseous.

In our solar system, the way that our planets spin while they rocket around the sun in their orbit gives them a night and day and allows multiples sides of the planet to get some face time with the sun. This isn’t the case for planetary objects like WASP-189b.

“They have a permanent day side, which is always exposed to the light of the star, and, accordingly, a permanent night side,” Lendl explained.

These details were discovered using data from the CHaracterising ExOPlanets Satellite (CHEOPS), the first European Space Agency (ESA) mission dedicated solely to extra-solar planets. The mission was launched in partnership with Switzerland, and benefitted from contributions from numerous European countries.

The satellite, with its mounted telescope, was launched in December of 2019, and has been orbiting 700 km above Earth ever since. Unlike many previous exoplanet-focused missions, CHEOPS is not interested in identifying new exoplanets, but was designed to peer closely at systems where we already knew an exoplanet is present.

Exoplanets — or extrasolar planets — are planets orbiting stars outside of our solar system, and because they’re so far away, we identify them not by finding a coloured speck in the sky, but by measuring dips in the light from stars.

When a star dims, it means something has passed in front of it, blocking some of the light from reaching the Earth. Using this “transit method,” researchers can figure out how large exoplanets are, how big or long their orbit is, and even what materials they are likely composed of.

There is also a change in light when a particularly bright planet goes behind its star, something called an “occultation.”

“Only a handful of planets are known to exist around stars this hot, and this system is by far the brightest,” Lendl said in an ESA release. “WASP-189b is also the brightest hot Jupiter that we can observe as it passes in front of or behind its star, making the whole system really intriguing.

“As the planet is so bright, there is actually a noticeable dip in the light we see coming from the system as it briefly slips out of view.”

While CHEOPS was pointed at WASP-189b, cataloguing all of its strange properties, researchers discovered that the star was unusual for more than just its bright blue colour.

It is spinning so rapidly that it is actually thicker at the equator, distorting the shape itself.

“The star itself is interesting — it’s not perfectly round, but larger and cooler at its equator than at the poles, making the poles of the star appear brighter,” said Lendl. “It’s spinning around so fast that it’s being pulled outwards at its equator! Adding to this asymmetry is the fact that WASP-189 b’s orbit is inclined; it doesn’t travel around the equator, but passes close to the star’s poles.”

This misaligned orbit implies that the planet had been formed further away from the star, and then been somehow pushed closer to it. Lendl suggested that this could mean the planet had interacted with other planets, or even other stars that had changed its orbital path.

According to the research, the planetary and star system is fairly young, which means researchers will be able to use this system to track the “atmospheric evolution of close-in gas giants.”

The new research is exciting to scientists not only for what it reveals about this planet and star, but for what it reveals about the telescope that provided such clear information.

“This first result from Cheops is hugely exciting: it is early definitive evidence that the mission is living up to its promise in terms of precision and performance,” Kate Isaak, CHEOPS project scientist at ESA, said in the ESA release.

Researchers point out in the paper that CHEOPS allowed them to refine and correct the size of the planet, which had been estimated incorrectly years earlier when the exoplanet’s existence was discovered by telescopes on the ground on Earth.

The paper concludes that the levels of the precision in the data shows that CHEOPS will be an invaluable tool in studying more exoplanets.

“We are expecting further spectacular findings on exoplanets thanks to observations with CHEOPS,” Benz said. “The next papers are already in preparation.”

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Buried lakes of salty water on Mars may provide conditions for life – MENAFN.COM

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(MENAFN – The Conversation) In 2018 a team of Italian scientists announced to the world that there was a lake on Mars . Using satellite radar data, the team detected a very bright area approximately 20 kilometres across located about 1.5 kilometres deep under the ice and dust of the south polar cap.

After analysis, they concluded that the bright area was a subglacial lake filled with liquid water. The discovery raised some fundamental questions.

Was this the only lake hidden beneath the ice on Mars? How could liquid water exist in the extreme cold of the Martian south polar region, where the average surface temperatures are lower than -100 °C?

After acquiring additional satellite data, my colleagues and I have discovered three more distinct ‘lakes’ near the one found in 2018 and confirmed that all four bodies contain liquid water.

Read more: Mars: mounting evidence for subglacial lakes, but could they really host life?

How can we see lakes under the ice on Mars?

The radar sounder MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is one of eight instruments on board the European Space Agency orbiter Mars Express. This scientific spacecraft has been circling the red planet since December 2003.

The orbiting radar directs radio ‘chirps’ toward the planetary surface. These signals are partly reflected back by the surface, and partly penetrate deeper, where they may be absorbed, scattered, or reflected back to the radar. Liquid water reflects radar signals better than many other materials, so the surface of a body of liquid water shines brightly in a radar image.

Radar sounders are used on Earth to detect subglacial lakes in Antarctica, Greenland and Canada. Here, a technique called radio-echo sounding (RES) is commonly used to analyse the signals.

There are some obvious differences between how radar sounding is used on Earth and on Mars. For a start, MARSIS operates from altitudes between 250 km and 900 km above the surface, it has a 40-metre long antenna, and it operates at much lower frequencies (1.8-5 MHz) than Earth-based radar sounders.




An illustration of the Mars Express satellite with the 40-metre MARSIS radar antenna. NASA / JPL / Corby Waste

These differences meant we had to do some work to adapt standard radio-echo sounding techniques for use with signals from MARSIS. However, we were able to analyse data from 134 MARSIS tracks acquired between 2010 and 2019 over an area 250 km wide and 300 km long near the south pole of Mars.

In this area, we identified three distinct bright patches around the lake already ‘seen’ in 2018. We then used an unconventional probabilistic method to confirm that the bright patches really do represent bodies of liquid water.

We also obtained a much clearer picture of the shape and extent of the lake discovered in 2018. It is still the largest of the bodies of water, measuring 20 km across on its shortest axis and 30 km on its longest.

How could liquid water exist beneath the Martian ice?

The surface temperatures in our study area are around -110 °C on average. The temperatures at the base of the ice cap may be slightly warmer, but still way below the freezing point of pure water.

So how can bodies of liquid water exist here, let alone persist for periods of time long enough for us to detect them?

After the first lake was found in 2018, other groups had suggested the area might be warmed from below by magma within the planet crust. However, there is to date no evidence this is the case, so we think extremely high salt levels in the water are a more likely explanation.

Read more: What on Earth could live in a salt water lake on Mars? An expert explains

Perchlorate salts, which contain chlorine, oxygen, and another element, such as magnesium or calcium, are everywhere in the Martian soil. These salts absorb moisture from the atmosphere and turn to liquid (this process is termed ‘deliquescence’), producing hypersaline aqueous solutions (brines), which crystallise at temperatures far below the freezing point of pure water. Furthermore, laboratory experiments have shown that solutions formed by deliquescence can stay liquid for long periods even after temperatures drop below their own freezing points.

We therefore suggested in our paper that the waters in the south polar subglacial lakes are ‘salty’. This is particularly fascinating, because it has been shown that brines like these can hold enough dissolved oxygen to support microbial life.

Could conditions be right for life beneath the ice?

Our discoveries raise new questions. Is the chemistry of the water in the south polar subglacial lakes suitable for life? How does this modify our definitions of habitable environments? Was there ever life on Mars?

To address these questions new experiments and new missions must be planned. In the meantime, we are gearing up to continue acquiring MARSIS data to collect as much evidence as possible from the Martian subsurface.

Each new piece of evidence brings us one step closer to answering some of the most fundamental scientific questions about Mars, the solar system and the universe.

Read more: Mars: mounting evidence for subglacial lakes, but could they really host life?

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Scientists find evidence of multiple underground lakes on Mars – Yahoo News Canada

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<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="Scientists believe they’ve found more evidence confirming the presence of a large reservoir of liquid water under the surface of Mars first discovered back in 2018. In fact, they believe they’ve found three more subsurface saltwater lakes surrounding that main one — a huge discovery, seeing as those lakes are potential habitats for life. As Nature notes in its post about the scientists’ paper, the first finding was met with lot of skepticism because it was only based on 29 observations from 2012 to 2015. This study and its findings were based on 134 observations made between 2012 and 2019.” data-reactid=”23″>Scientists believe they’ve found more evidence confirming the presence of a large reservoir of liquid water under the surface of Mars first discovered back in 2018. In fact, they believe they’ve found three more subsurface saltwater lakes surrounding that main one — a huge discovery, seeing as those lakes are potential habitats for life. As Nature notes in its post about the scientists’ paper, the first finding was met with lot of skepticism because it was only based on 29 observations from 2012 to 2015. This study and its findings were based on 134 observations made between 2012 and 2019.

The team used data from a radar instrument on the European Space Agency’s (ESA) Mars Express spacecraft to investigate the planet’s southern polar region. Mars Advanced Radar for Subsurface and Ionosphere Sounding or MARSIS, as the instrument is called, is capable of sending out radio waves that bounce off materials on the planet’s surface. Different materials reflect those signals differently, and the same technique is used to find subsurface glacial lakes here on Earth.

Upon observing an area that’s around 75,000 square kilometers in size, they found locations that reflected those signals back in a way that indicates the presence of water trapped underneath a kilometer of ice. The main lake, the one discovered back in 2018, measures 30 kilometers or 19 miles across, while each of the three smaller lakes surrounding it are a few kilometers across.

<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="While the scientists’ findings are promising, some experts still believe we won’t find lakes on the red planet at all. Jack Holt, a planetary scientist part of NASA’s Mars Reconnaissance Orbiter program, doesn’t believe there’s enough heat flow under the surface of the planet for water to remain liquid. And even if we do find liquid water under Martian ice, that won’t automatically mean we’ll also find life. See, the lakes have to be very salty to remain liquid, but their salt content must not exceed five times that of seawater to be able to support life. As John Priscu, an environmental scientist at Montana State University, told Nature:” data-reactid=”27″>While the scientists’ findings are promising, some experts still believe we won’t find lakes on the red planet at all. Jack Holt, a planetary scientist part of NASA’s Mars Reconnaissance Orbiter program, doesn’t believe there’s enough heat flow under the surface of the planet for water to remain liquid. And even if we do find liquid water under Martian ice, that won’t automatically mean we’ll also find life. See, the lakes have to be very salty to remain liquid, but their salt content must not exceed five times that of seawater to be able to support life. As John Priscu, an environmental scientist at Montana State University, told Nature:

“There’s not much active life in… briny pools in Antarctica. They’re just pickled. And that might be the case [on Mars].”

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