Sic Itur Ad Astra





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It's Coming! A rare green comet will appear in the Aussie skies visible for the first time in 50,000 years. 

The comet - though notoriously unpredictable - has been steadily brightening as it approaches the sun, and should be easy to spot with binoculars
The comet - though notoriously unpredictable - has been steadily brightening as it approaches the sun, and should be easy to spot with binoculars

 The recently discovered comet, which was given the catchy name C/2022 E3 (ZTF).  In Australia February 2023 is the last month of Summer in the Southern Hemisphere. Full Moon is the 6th of February, and the New Moon is the 20th of February.

The buzz around Comet C/2022 E3 (ZTF) has really hit fever pitch and has been in the media on TV news. It's been renamed "The Green Comet" but won't appear green in either binoculars or a telescope. The ghostly green glow will only become much clearer in photographs. 

You will be able to see Comet C/2022 E3 (ZTF) with just your eyes even under dark skies. You'll be able to spot it in with almost any binoculars or even a small telescope. You'll see it clearly. It's near Mars on around the 10-12th of February and in the vicinity of the Great Orion Nebula (M42) towards the end of the month. Mars can be found easily in the early evening,- it looks like a red coloured 'star.' Put a pair of 10x50 (or similar) binoculars up to Mars and go slightly to the left and you should see it.

Comets can be distinguished from stars by their streaking tails of dust and energised particles - which will cause this one to glow bright green. The glow is caused by an envelope that firms around the comet as it passed by the sun and its icy exterior instantly turns into gas.  Discovered in March last year by astronomers using the Zwicky Transient Facility's wide-field survey camera in southern California, the comet passes by the far outer reaches of the solar system each time it orbits the sun - which is why it's taken so long to swing by Earth once more.

It last made its appearance over our blue planet about 50,000 years ago, when a mere two million humans roamed and our ancestors the Neanderthals were not yet extinct. According to NASA, the comet - though notoriously unpredictable - has been steadily brightening as it approaches the sun, and should be easy to spot with binoculars

Quasar Publishing - the same folks behind the popular Australian astronomy annual - have produced this excellent graphic which shows the path of Comet C/2022 E3 (ZTF) over the coming month or so.

However - the one thing we can tell you for certain is the "Green Comet" won't appear Green when viewed through binoculars or a telescope. The green colours you've see online or in the news are only visible via long exposure photographs. They can't be seen visually even in larger telescopes. The views will be stunning, but they will be in black and white to your eyes.

If you see a fuzzy patch with a "tail" leading away from it and it's not green, don't think "no, that's not it". You're more than likely looking at the comet! While it might not be as spectacular as it appears in photos taken with expensive gear, what you're looking at is an ancient part of the Solar System whizzing around the Sun before it heads back out into deep space.

Astronomers See Flashes on the Sun That Could be a Sign of an Upcoming Flare

A moderate solar flare erupts on the sun July 8, 2014 in this image from NASA's Solar Dynamics Observatory. Credit: NASA/SDO
A moderate solar flare erupts on the sun July 8, 2014 in this image from NASA's Solar Dynamics Observatory. Credit: NASA/SDO
A moderate solar flare erupts on the sun July 8, 2014  NASA's Solar Dynamics Observatory. Credit: NASA/SDO
A moderate solar flare erupts on the sun July 8, 2014 NASA's Solar Dynamics Observatory. Credit: NASA/SDO

Using data from the Solar Dynamics Observatory, scientists have discovered new clues that could help predict when and where the next solar flare might blast from the Sun.

Researchers were able to identify small flashes in the upper layers of the corona - the Sun's atmosphere - found above regions that would later flare in energetic bursts of light and particles released from the Sun. The scientists compared the flashes to small sparklers before the big fireworks.

"We can get some very different information in the corona than we get from the photosphere, or 'surface' of the Sun," said KD Leka, lead author on the new study from Nagoya University in Japan, in a NASA press release. "Our results may give us a new marker to distinguish which active regions are likely to flare soon and which will stay quiet over an upcoming period of time."

Since it launched in 2010, the Solar Dynamics Observatory has helped scientists understand better what causes solar flares. One of the main goals of the mission was to be able to create forecasts for predicting activity on the Sun.

Scientists have previously studied how changes in the Sun's magnetic field can cause flares, helping them to predict when some flares would occure. Additionally, other teams have modeled how activity in lower layers of the Sun's atmosphere - such as the photosphere and chromosphere - can indicate impending flare activity in active regions, which are often marked by groups of sunspots. The new findings, published in The Astrophysical Journal, add to that picture.

"With this research, we are really starting to dig deeper," said Karin Dissauer from NorthWest Research Associates, or NWRA, who was instrumental in putting together an image database of the Sun's active regions captured by SDO for the past eight years. "Down the road, combining all this information from the surface up through the corona should allow forecasters to make better predictions about when and where solar flares will happen."

The new database makes it easier for scientists to use data from SDO's Atmospheric Imaging Assembly (AIA) large statistical studies. "It's the first time a database like this is readily available for the scientific community, and it will be very useful for studying many topics, not just flare-ready active regions," Dissauer said.

The NWRA team studied a large sample of active regions from the database, and their analysis revealed there are frequently small, intense brightness changes in the corona before the solar flares. These and other new insights will give researchers a better understanding of the physics taking place in these magnetically active regions, with the goal of developing new tools to predict solar flares.

The team said their methods could eventually help improve predictions of flares and space weather storms. Space weather can affect Earth in many ways: producing auroras, endangering astronauts, disrupting radio communications, and even causing large electrical blackouts.

Astronomers Find a Dozen More Moons for Jupiter

All of the newly discovered moons are small and far out, taking more than 340 days to orbit Jupiter.
All of the newly discovered moons are small and far out, taking more than 340 days to orbit Jupiter.

The discovery of a dozen new moons for Jupiter makes the king of planets the king of moons, too - at least for now. The biggest planet in the solar system now has the largest family of moons. Since December 20th, the Minor Planet Center (MPC) has published orbits for 12 previously unreported moons of Jupiter. 

More publications are expected, says Scott Sheppard (Carnegie Institute for Science), who recently submitted observations of the Jovian system taken between 2021 and 2022. The discoveries bring the list of Jovian moons to 92, a hefty 15% increase from the previous tally of 80.

The MPC's orbital calculations confirm the new objects are in orbit around Jupiter. Other data from Sheppard's observations even enabled recovery of the last "missing" Jovian moon, S/2003 J 10; the newest observations extended the track of its orbit to 18 years.

Jupiter vs. Saturn

The new finds put Jupiter's lunar family count well ahead of Saturn's 83 confirmed moons. However, while Jupiter may have the most moons for now, Saturn might catch up. A search for objects with sizes down to about 3 kilometers across that are moving along with the gas giants found three times more near Saturn than near Jupiter. The more numerous Saturnian objects might have come from a collision that disrupted a larger moon a few hundred million years ago. (The fragments have not been tracked carefully enough to count as moons yet, though.)

If we could count all moons measuring at least 3 kilometers across, "Saturn would have more moons than all the rest of the solar system," says Brett Gladman (University of British Columbia, Canada), who helped identify the new Saturnian objects but was not involved in the Jovian observations.

New Moons

All of the newly discovered moons are small and far out, taking more than 340 days to orbit Jupiter. Nine of the 12 are among the 71 outermost Jovian moons, whose orbits are more than 550 days. Jupiter probably captured these moons, as evidenced by their retrograde orbits, opposite in direction to the inner moons. Only five of all the retrograde moons are larger than 8 kilometers (5 miles); Sheppard says the smaller moons probably formed when collisions fragmented larger objects.

Three of the newly discovered moons are in among 13 others that orbit in a prograde direction and lie between the large, close-in Galilean moons and the far-out retrograde moons. These prograde moons are thought to have formed where they are.

They're harder to find than the more distant retrograde moons, though, says Sheppard. "The reason is that they are closer to Jupiter and the scattered light from the planet is tremendous," he says. That light obscures them in the sky. Five were found before 2000, and only eight more have been discovered since then.

Besides the interest in their origins, these prograde moons could make suitable targets for a flyby from an upcoming mission. Three missions are in the works for the Jupiter system: the European Space Agency's Jupiter Icy Moon Explorer (JUICE), scheduled for launch in April; NASA's Europa Clipper , set for launch late next year; and a Chinese mission being considered for the 2030s.

Beyond the Galilean Moons

The prograde objects outside the Galilean moons fall into two groups: the nine moons of the Himalia group orbit 11 to 12 million km from Jupiter, and the more distant duo in the Carpo group at 17 million km. The new discoveries added two of Himalia's current tally of nine, and one of Carpo's duo.

Searches for prograde moons outside these groups turned up nothing. In the yawning gap between Himalia and the Galilean moons, there's only one moon known: Themisto, a 9-kilometer object discovered by Elizabeth Roemer and Charles Kowal in 1975 but not recovered until 2000. It orbits 7.5 million kilometers (4.6 million miles) from Jupiter, roughly halfway between Callisto at 1.9 million km and the group of prograde moons starting at 11 million km.

That's a big hole. "We have searched very deeply for objects near Themisto, and have found nothing else to date," says Sheppard. He says glare from Jupiter is so strong it would hide anything smaller than 3 kilometers across.

A single prograde moon, the 1-km Valetudo, orbits beyond the Carpo group, at 19 million km from Jupiter. After discovering it in 2018, Sheppard called Valetudo an "oddball" because its orbit crosses those of a few retrograde moons. This highly unstable situation is likely to lead to head-on collisions that would shatter one or both objects. Sheppard adds that Valetudo might be all that remains of a larger prograde moon that had suffered from earlier collisions. No other members have been found to date.

Discovering New Moons

Discoveries of small moons of Jupiter or Saturn are typically reported in Minor Planet Center Electronic Circulars. But those reports take time. Analyzing observations and calculating trajectories is more complex for planetary moons than for asteroids or comets, because a moon's path depends on both the gravity of its planet as well as the Sun. Observations must also track the moon for a full orbit to show it really orbits the planet, and the outer moons of Jupiter take about two years to orbit the planet. 

For asteroids and comets, on the other hand, a few weeks of observations may suffice to predict their course because their path depends only on the Sun. We can expect more reports as Sheppard, Gladman, and others continue the hunt for new moons in the outer solar system.

Found - Potential Alien 'Technosignatures' Hidden in Radio Signals From Space

While scientists aren't holding their breath, AI could be a powerful tool in the ongoing search for alien life.
While scientists aren't holding their breath, AI could be a powerful tool in the ongoing search for alien life.

Searching the skies for UFOs or homesick aliens is practically an American pastime, and no one does it better than the SETI Institute (SETI meaning Search for Extraterrestrial Intelligence).

Established in 1984, SETI has made it their mission to scan the skies for radio signals comprised of non-Earth based "technosignatures" that may belong to alien tech. Such signals-which may indicate communications technology in use, and thus intelligence-are sought after by scientists looking for signs of alien life. So far, this decades-long search has yet to turn up any convincing leads, but a new paper published Monday in the journal Nature Astronomy is hoping to change that by using machine learning to tackle the problem.

Using telescope data that was first collected in 2016, the machine-learning algorithm analyzedver 480 hours of data from 820 stars and identified eight signals of interest that previous algorithms had not detected.

Peter Ma is first author on the paper and an undergraduate student at the University of Toronto. He told Motherboard in an email that while AI has been applied to SETI's radio data in the past, this new approach takes the search completely out of human hands.

"Previously people have inserted ML [machine learning] components into various pipelines to help with the search," Ma said. "This work relies entirely on just the neural network without any traditional algorithms supporting it and produced results that traditional algorithms did not pick up."

Radio data streaming in from outer space is an abundant resource, but it's also one that can be easily muddled with our own Earth-based radio signals. Ma said that signals of interest that are plucked from this haze are ones that "are narrow band, doppler drifting signals originating from some extraterrestrial source."

In other words, radio signals that are moving and fall into a particular range of frequencies. However, how these signals may morph over time or distance is still an open question.

Looking for these signals in the data can be like looking for a needle in a haystack-time consuming and tedious-but that's where machine-learning can help. Ma and colleagues designed their neural network to identify and then classify what it "thinks" the most important features of the SETI data while simultaneously trying to filter out Earth-based interference.

In addition to being twice as fast as traditional algorithms, Ma said that using a neural network to study this data also allows for a type of out-of-the-box thinking that human-dictated algorithms struggle to achieve.

"Traditional algorithms operate on a given set of instructions designed by us... thus the algorithm will only ever discover what we tell it to find," he said. "The issue is that the nature of an ET signal is not completely known... Hence our proposed approach is to just learn it."

Ma and colleagues' neural network was able to find eight unique signals hidden in the data that may potentially be from extraterrestrial sources, but research hasn't yet been done to confirm these. And while further analysis may be able to confirm these sources as non-Earth based, that doesn't mean scientists will know exactly what kind of tech they're connected to, Ma said.

In the best case scenario, these signals may include embedded information about the engineering of the technology or even a collection of technosignatures from an alien civilization. "We don't count on this, though," Ma said. 

Stars Disappear Before Our Eyes: Startling Analysis From Globe at Night

Light Pollution Impact 1 – From excellent dark sky (left) to inner city sky (right). This graphic illustrates how the greater the amount of light pollution, and therefore skyglow, the fewer the stars that are visible.
Light Pollution Impact 1 – From excellent dark sky (left) to inner city sky (right). This graphic illustrates how the greater the amount of light pollution, and therefore skyglow, the fewer the stars that are visible.

A startling analysis from Globe at Night - a citizen science program run by NSF's NOIRLab - concludes that stars are disappearing from human sight at an astonishing rate. The study finds that, to human eyes, artificial lighting has dulled the night sky more rapidly than indicated by satellite measurements. The study published in the journal Science showcases the unique contributions that citizen scientists can make in essential fields of research.

From the glowing arc of the Milky Way to dozens of intricate constellations, the unaided human eye should be able to perceive several thousand stars on a clear, dark night. Unfortunately, growing light pollution has robbed about 30% of people around the globe and approximately 80% of people in the United States of the nightly view of their home galaxy. A new paper published in the journal Science concludes that the problem is getting rapidly worse.

New citizen-science-based research sheds alarming light on the problem of 'skyglow' - the diffuse illumination of the night sky that is a form of light pollution. The data for this study came from crowd-sourced observations collected from around the world as part of Globe at Night, a program run by NSF's NOIRLab and developed by NOIRLab astronomer Connie Walker. The research reveals that skyglow is increasing more rapidly than shown in satellite measurements of Earth's surface brightness at night.

"At this rate of change, a child born in a location where 250 stars were visible would be able to see only abound100 by the time they turned 18," said Christopher Kyba, a researcher at the German Research Centre for Geosciences and lead author of the paper detailing these results.

Light pollution is a familiar problem that has many detrimental effects, not only on the practice of astronomy. It also has an impact on human health and wildlife, since it disrupts the cyclical transition from sunlight to starlight that biological systems have evolved alongside. Furthermore, the loss of visible stars is a poignant loss of human cultural heritage. Until relatively recently, humans throughout history had an impressive view of the starry night sky, and the effect of this nightly spectacle is evident in ancient cultures, from the myths it inspired to the structures that were built in alignment with celestial bodies.

Despite being a well-recognized issue, however, the changes in sky brightness over time are not well documented, particularly on a global scale.

Globe at Night has been gathering data on stellar visibility every year since 2006.[1] Anyone can submit observations through the Globe at Night web application on a desktop or smartphone. After entering the relevant date, time and location, participants are shown a number of star maps. They then record which one best matches what they can see in the sky without any telescopes or other instruments.

This gives an estimate of what is called the naked eye limiting magnitude, which is a measure of how bright an object must be in order to be seen. This can be used to estimate the brightness of skyglow, because as the sky brightens, the fainter objects disappear from sight.

The authors of the paper analyzed more than 50,000 observations submitted to Globe at Night between 2011 and 2022, ensuring consistency by omitting entries that were affected by factors including cloud cover and moonlight. They focused on data from Europe and North America, since these regions had a sufficient distribution of observations across the land area as well as throughout the decade studied. The paper notes that the sky is likely brightening more quickly in developing countries, where satellite observations indicate the prevalence of artificial lighting is growing at a higher rate.

After devising a new method to convert these observations into estimates of the change in skyglow, the authors found that the loss of visible stars reported by Globe at Night indicates an increase in sky brightness of 9.6% per year over the past decade. This is much greater than the roughly 2% per year global increase in surface brightness measured by satellites.

"This shows that existing satellites aren't sufficient to study how Earth's night is changing," said Kyba. "We've developed a way to 'translate' Globe at Night observations of star visibility made at different locations from year to year into continent-wide trends of sky brightness change. That shows that Globe at Night isn't just an interesting outreach activity, it's an essential measurement of one of Earth's environmental variables."

Existing satellites are not well suited to measuring skyglow as it appears to humans, because there are no current instruments monitoring the whole Earth that can detect wavelengths shorter than 500 nanometers, which corresponds to the color cyan, or greenish blue. Shorter wavelengths, however, contribute disproportionately to skyglow, because they scatter more effectively in the atmosphere. White LEDs, now increasingly commonly used in high-efficiency outdoor lighting, have a peak in emission between 400 and 500 nanometers.

"Since human eyes are more sensitive to these shorter wavelengths at nighttime, LED lights have a strong effect on our perception of sky brightness," said Kyba. "This could be one of the reasons behind the discrepancy between satellite measurements and the sky conditions reported by Globe at Night participants."

Beyond wavelength differences, space-based instruments do not measure light emitted horizontally very well, such as from illuminated signs or windows, but these sources are significant contributors to skyglow as seen from the ground. Crowd-sourced observations will therefore always be invaluable for investigating the direct human effects of sky brightness.

"The increase in skyglow over the past decade underscores the importance of redoubling our efforts and developing new strategies to protect dark skies," said Walker. "The Globe at Night dataset is indispensable in our ongoing evaluation of changes in skyglow, and we encourage everyone who can to get involved to help protect the starry night sky."

NASA and DARPA plan to test a nuclear-powered rocket that could take humans to Mars in record time

An artist's illustration of the Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will be used to test a nuclear thermal rocket engine.
An artist's illustration of the Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will be used to test a nuclear thermal rocket engine.

NASA is investing in plans to test a nuclear-propelled rocket by 2027 that could reach Mars within weeks, the agency's chief Bill Nelson said in a statement this week. The agency is teaming up with the Pentagon's Defense Advanced Research Projects Agency (DARPA) to make a rocket that could reach Mars in record time. They aim to test that rocket by 2027.

"With the help of this new technology, astronauts could journey to and from deep space faster than ever - a major capability to prepare for crewed missions to Mars," NASA administrator Bill Nelson said Tuesday. NASA's recent successful Artemis I mission to the moon was only the first step in its plans to advance human space exploration. The agency aims to put humans on Mars, for the first time, by the late 2030s or early 2040s.

Early missions to the red planet would only last about 30 days, so making sure that travel time is minimized is crucial. Nuclear thermal propulsion is not a new idea for rockets - the concept was first tested in the 60s. It relies on using a nuclear reactor to heat a liquid propellant such as hydrogen. That heat converts the liquid to gas. As it expands, the gas is funneled through a nozzle, which generates thrust, propelling the rocket forward.

These rockets would be three or more times more efficient than traditional chemical-based rocket engines, and much faster. Not only would they be able to carry a heavier workload, but they would also travel quicker than their chemical counterparts, per the press release. Transit to Mars using a nuclear-powered rocket could take four months, a lot shorter than the usual nine months for older rocket models, Reuters reported.

NASA has also funded an application to develop a concept for a new type of nuclear-thermal propulsion system. If that concept proves to work, it could reduce travel time to Mars to just 45 days, per the concept application. 


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'Stargazing' - Astronomy Nights At Your Place

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