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ABC News
20-05-2025
- Science
- ABC News
The metre originated in the French Revolution, but its definition has changed many times since
The next time you pick up a bag of spuds from the supermarket or fill up the car with petrol, you can thank a treaty signed 150 years ago for the metric system that underpins daily life. On May 20, 1875, delegates from 17 countries assembled on a Parisian spring day and signed the Metre Convention, also known as the Treaty of the Metre. At the time, it wasn't uncommon for countries, states and even cities to have entirely different ways of measuring distance and mass, hampering trade and holding back progress in science. To standardise and unify these definitions, the Treaty of the Metre established the International Bureau of Weights and Measures, which initially defined the metre and kilogram. Over the years, more countries signed the Treaty of the Metre, including Australia in November 1947. A handful of other units of measurement were also included to form the International System of Units, the basis of the metric system. But the metre's inception predates the treaty that bears its name by nearly 100 years. And its story begins during the French Revolution. During the late 1700s, revolutionaries shaping the new republic of France shed old traditions bound to royalty and religion. This reinvention included creating a new system of measurement. This system would be available to everyone, and be tied to fundamental properties of nature, "not from the length of the king's arm, or something that changed over time", Bruce Warrington, CEO and chief metrologist at the National Measurement Institute, says. So mathematicians and scientists of the time decreed that the length of a metre — from the Greek word "metron", meaning "a measure" — was equal to one 10-millionth of the distance from the North Pole to the equator through the Paris Observatory. It fell to a pair of astronomers to calculate this distance, and after seven years, in 1799, they presented their final measurement to the French Academy of Sciences which made a "Metre of the Archives" in the form of a platinum bar. (It was later found the astronomers were a bit off in their calculations, and the metre as we know it is 0.2 millimetres shorter than it should've been.) The Metre of the Archives and its copies were eventually replaced by around 30 metre bars made of a stable platinum-iridium alloy. They were distributed around the world in the late 1890s, and remained the "standard" metre for decades. But as science progressed, the definition of the metre changed too. This change started early last century, when scientists discovered they could measure distances using light. Light travels in waves. If you know the distance between each wave — called the wavelength, literally the length of the wave — it's possible to use light "as a very fine ruler", Dr Warrington says. And in 1960, the platinum alloy bars were out and a new definition of the metre was introduced. Pass an electrical current through a lamp filled with krypton gas and the krypton atoms throw off light, including a reddish orange wavelength. One metre equalled 1,650,763.73 times the wavelength of this specific reddish orange light. Meanwhile, electronics fabrication kicked off and the scale of manufacturing shrunk to the incredibly tiny. Think transistors in a smartphone integrated circuit, which are only a few billionths of a metre wide. "So you need rulers that can check for and control the quality of that manufacturing at that level," Dr Warrington says — something the krypton lamp metre definition could not do. Since 1960, there'd been a lot of progress made on measuring time accurately with atomic clocks. Their "ticking" is produced by oscillations of radiation emitted when atoms are bathed in laser light. And they can tick billions of times every second. This new ability to divvy up the second into increasingly tinier slices, coupled with a universal physical constant, the speed of light, redefined the metre. From 1983, a metre was considered the distance that light travels in a vacuum in 1/299,792,458 of a second (because light travels 299,792,458 metres per second). This new definition incorporating time and the speed of light opened up new ways of measuring length, Dr Warrington says. For instance, scientists use it to accurately measure Earth's distance to the Moon. "The Apollo astronauts left a kind of fancy mirror on the surface of the Moon, and to this day, you can still fire a laser at that reflector, and time the round trip for the light to go all the way to the Moon and back," Dr Warrington says. "And you can turn that into a very careful measurement of the distance between the Earth and the Moon." These measurements show the Moon is slowly pulling away from Earth at around 3.8 centimetres each year. Even as the metre and other units of measurement were being redefined, it was up to each Metre Treaty signatory to adopt the metric system in their own time. It took Australia more than 20 years after signing the Metre Treaty to officially adopt the metric system when the Metric Conversion Act was passed in 1970. Other countries have been far slower to go metric. One of the original signatories of the Metre Treaty was … the US. Today, while day-to-day life in the US tends to use imperial units, the metric system is legally recognised and is "at the core of its civil measurement", Dr Warrington says. "So its national standards [for mass and distance] are the kilogram and the metre, just like everybody else's." Even in Australia today you don't have to look far to see imperial units in, for example, men's trouser waistbands and television screen size. One area that still suffers inconsistencies in measurement is in the kitchen, Dr Warrington says. "I find it slightly frustrating as a professional measurement nerd that an Australian tablespoon is four teaspoons, whereas almost everywhere else in the rest of the world, it's three teaspoons. For more on the history of the metre, check out the full episode of Lab Notes.
Yahoo
19-04-2025
- Science
- Yahoo
Scientists finally answer one of space's biggest mysteries which could answer how life on Earth began
Scientists have finally found an answer to one of space's biggest mysteries, and the answer could even lead to finally figuring out how life on earth began. When it comes to exploring space, every time scientists uncover or learn one thing, it does seem to answer 100 more questions. This time, however, the burning space question is not 'Why did they send Katy Perry to space' or 'Why did Katy Perry sing What a Wonderful World in space, but instead something that has been pondered for years. Essentially, carbon-rich asteroids are abundant in space, with an asteroid stuffed to the brim with carbon being an incredibly common find. On Earth, however, when you do come across meteorites, less than five per cent are carbon-rich. You may be wondering, what does this have to do with life on Earth, and why do we care? Well, the reason is that carbon-rich asteroids contain water and organic molecules, both of which are key to the creation of life. Therefore, in order to take a massive step towards better understanding how the creation of life occurred, they first need to answer why carbon-rich asteroids are so rare on Earth compared to in space. Scientists have spent years trying to figure this out and have now got an answer. A peer-reviewed study, published by Nature Astronomy, featured international researchers who investigated the phenomena. This included scientists from Curtin University's School of Earth and Planetary Sciences, the International Centre for Radio Astronomy (ICRAR), the Paris Observatory, and many more. The study analysed over 8,000 meteoroids and impacts to discover that the Earth and the Sun both operate as 'giant filters'. Earth and the sun, therefore, destroy carbon-rich meteoroids before they reach the ground due to their fragile nature. Dr Hadrien Devillepoix, a co-author on the research, said: 'We've long suspected weak, carbonaceous material doesn't survive atmospheric entry. 'What this research shows is many of these meteoroids don't even make it that far: they break apart from being heated repeatedly as they pass close to the Sun. 'The ones that do survive getting cooked in space are more likely to also make it through Earth's atmosphere.' Dr Patrick Shober, of the Paris Observatory, said: 'Carbon-rich meteorites are some of the most chemically primitive materials we can study — they contain water, organic molecules and even amino acids. 'However, we have so few of them in our meteorite collections that we risk having an incomplete picture of what's actually out there in space and how the building blocks of life arrived on Earth. 'Understanding what gets filtered out and why is key to reconstructing our solar system's history and the conditions that made life possible.' He finally added: 'This finding could influence future asteroid missions, impact hazard assessments and even theories on how Earth got its water and organic compounds to allow life to begin.'
Yahoo
10-04-2025
- Science
- Yahoo
We Were Wrong About Uranus: New Study Solves Long-Standing Mysteries
New observations have revealed that we were wrong about the length of a day on Uranus. According to the most precise measurements yet of the stinky planet's rotation rate, a full day on Uranus lasts 17 hours, 14 minutes, and 52 seconds. That's 28 whole seconds longer than we thought, based on data collected by Voyager 2 on its Uranus flyby in 1986. That might not seem like a big deal… but it is actually huge. "Our measurement not only provides an essential reference for the planetary science community but also resolves a long-standing issue: previous coordinate systems based on outdated rotation periods quickly became inaccurate, making it impossible to track Uranus' magnetic poles over time," explains astrophysicist Laurent Lamy of the Paris Observatory. Uranus and Neptune are the two outermost worlds of the Solar System, at significantly greater distances from the Sun than the rest of the planets. Uranus is twice the orbital distance of Saturn; Neptune is more than three times Saturn's orbital distance. Because they are so far, Uranus and Neptune appear small and dim, which makes them difficult to study; in addition, that distance makes them a longer trek for spacecraft, so only the Voyager mission has been close, decades ago. This means the information we have about the outer Solar System's ice giants is limited, and may potentially be biased by the particular conditions affecting the planets at the time of the flybys. Getting new information, on the other hand, is a bit of a challenge. The inaccuracy in our assumption about the length of the Uranian day has resulted in some confusion. One of the biggest problems was that, without an accurate length-of-day, the orientation of Uranus's magnetic poles was lost just a few years after the Voyager 2 flyby. To remeasure the length of a Uranus day, Lamy and his colleagues made a careful study of data collected by the Hubble Space Telescope between 2011 and 2022. In that timespan, the telescope repeatedly observed the planet's ultraviolet auroras, which are generated a lot like the aurora here on Earth. Particles borne on the solar wind smack into the planetary magnetosphere, and are whisked away and accelerated along the lines of the magnetic field to the polar latitudes, where they are dumped into the upper atmosphere. Interactions between particles in the atmosphere and the incoming solar particles make a glow in the sky. One of the funny things about Uranus is that its rotational axis is almost parallel to the ecliptic, the orbital plane on which the planets all more or less move around the Sun, compared to the almost-perpendicular orientation of the rest of the planets. This orientation has made its magnetic poles a little harder to find. By tracking the ultraviolet auroras, Lamy and his colleagues were able to locate and trace the poles, and used that information to precisely measure the length of the Uranian day. This measurement is p-r-e-c-i-s-e – the most precise yet for a giant planet, the researchers say, even more precise than measurements of Jupiter's rotation rate. The technique used to measure the rate can thus be applied to the rest of the giant worlds in the Solar System to obtain precise measurements of their inner rotation rates. "With this new longitude system, we can now compare auroral observations spanning nearly 40 years and even plan for the upcoming Uranus mission," Lamy says. The research has been published in Nature Astronomy. Infrared AI Camera Proposed to Scan Earth's Skies For Signs of Alien Visitors 'City Killer' Asteroid's Origin Traced to an Unexpected Part of The Solar System ESA Report Says There's Too Much Junk in Earth Orbit Trunk
Yahoo
08-04-2025
- Science
- Yahoo
A day on Uranus is actually longer than we thought, Hubble Telescope reveals
When you buy through links on our articles, Future and its syndication partners may earn a commission. Uranus just got a little more time on its hands. A fresh analysis of a decade's worth of Hubble Space Telescope observations shows Uranus takes 17 hours, 14 minutes and 52 seconds to complete a full rotation — that's 28 seconds longer than the estimate provided by NASA's Voyager 2 spacecraft nearly four decades ago. In January 1986, Voyager 2 became the first — and so far the only — spacecraft to explore Uranus, and with its data, astronomers pegged the ice giant's rotation period at 17 hours, 14 minutes and 24 seconds. This estimate was based on radio signals emitted by the pale turquoise planet's auroras and direct magnetic field measurements. This figure became the bedrock for calculating coordinates on the enigmatic world and mapping its surface. Scientists may need to rethink some of those maps, a new study suggests. The initial estimate based on Voyager 2 data carried inherent uncertainties that led to a 180-degree error in Uranus' longitude, causing the orientation of its magnetic axis to become "completely lost" within just a couple of years after the spacecraft's flyby. Consequently, coordinate systems relying on the outdated rotation period quickly lost their reliability, according to the study. To resolve this issue, a team of astronomers led by Laurent Lamy of the Paris Observatory tracked the motion of Uranus's auroras using Hubble Space Telescope data collected between 2011 and 2022. By tracking the movement of these luminous displays over a little more than a decade, the researchers were able to precisely pinpoint the planet's magnetic poles and, in turn, a better estimate of its rotational period. "The continuous observations from Hubble were crucial," Lamy added in a statement. "Without this wealth of data, it would have been impossible to detect the periodic signal with the level of accuracy we achieved." This approach can now be used to determine the rotation rate of any celestial object with a magnetic field and auroras, not only in our solar system but also on exoplanets and other faraway worlds, the researchers say. Related Stories: — Changing seasons on Uranus tracked across 20 years by Hubble Space Telescope — Spiral starburst galaxy glows in gorgeous Hubble Telescope image — Hubble Telescope discovers a new '3-body problem' puzzle among Kuiper Belt asteroids (video) The updated estimate of Uranus' rotation period has provided a much more reliable coordinate system for the ice giant, one that is expected to remain accurate for decades until future missions can offer even more refined data, according to the new study. The improved estimate could also be useful in planning future missions to Uranus, particularly in defining orbital tours and selecting suitable atmospheric entry sites, Lamy and his team wrote in the new study. This research is described in a paper published Monday (April 7) in the journal Nature Astronomy.
The Independent
07-04-2025
- Science
- The Independent
A day on Uranus is actually longer than previously thought
New observations have revealed that a day on Uranus is slightly longer than previously thought. According to scientists, data collected by the Hubble Space Telescope indicates that Uranus completes a full rotation in 17 hours, 14 minutes, and 52 seconds. This is 28 seconds longer than estimations made by NASA 's Voyager 2 spacecraft in the 1980s. A team led by French scientists analysed a decade's worth of aurora observations on the ice giant to monitor its magnetic poles, which allowed for a more precise calculation of Uranus's rotation period. Uranus, the seventh planet from the sun, takes approximately 84 Earth years to orbit the sun. Laurent Lamy of the Paris Observatory, the lead author of the study, stated that "The continuous observations from Hubble were crucial" in obtaining these findings. Lamy and his team suggest that this method could be applied to determine the rotation of any celestial body that features auroras and a magnetosphere. The findings, published in Nature Astronomy, coincide with the upcoming 35th anniversary of Hubble's launch. The space telescope was deployed into orbit by NASA's space shuttle Discovery on April 24, 1990.
