Nereide

Physicist interested in Astrophysics & Particle Physics| Research in Math & Science Edu| Math & Science Writer| Teacher & Teacher Trainer| WomenInSTEM

[Nereide @Nereide]

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#Voyager1 is about to reach a milestone no other human-made object has ever touched: one light-day away from Earth.

On November 18, 2026 at 5:16 EST it will have traveled roughly 26 billion km.

A journey of almost 50 years.

A light-day is just how far light goes in 24 hours.

Light travels around 300,000 km a second, which adds up to roughly 26 billion km in a day.
It’s the clearest way to measure enormous space distances, because nothing goes faster than light.

The Moon is 1.3 light-seconds away. The Sun takes 8 minutes and 20 seconds. Neptune sits a bit past 4 light-hours. Proxima Centauri is the nearest star, 4.24 light-years off. Andromeda is around 2.5 million light-years away.
A light-day is already enormous.

Voyager 1’s doing about 61,000 km/h right now, pointed at Gliese 445 over in Ursa Minor. Forty thousand years from now it’ll swing past that star at roughly 1.7 light-years.
Even at that speed, compared to light it moves like a snail.

It took #Voyager1 49 years, 2 months and 11 days to cover one light-day. Voyager 2 took a different route so it could visit Uranus and Neptune — it won’t reach the same distance until 2035.

November 18 is worth marking: the first human-made object one light-day from Earth.

[Nereide @Nereide]

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#Voyager1 is about to reach a milestone no other human-made object has ever touched: one light-day away from Earth.

On November 18, 2026 at 5:16 EST it will have traveled roughly 26 billion km.

A journey of almost 50 years.

A light-day is just how far light goes in 24 hours.

Light travels around 300,000 km a second, which adds up to roughly 26 billion km in a day.
It’s the clearest way to measure enormous space distances, because nothing goes faster than light.

The Moon is 1.3 light-seconds away. The Sun takes 8 minutes and 20 seconds. Neptune sits a bit past 4 light-hours. Proxima Centauri is the nearest star, 4.24 light-years off. Andromeda is around 2.5 million light-years away.
A light-day is already enormous.

Voyager 1’s doing about 61,000 km/h right now, pointed at Gliese 445 over in Ursa Minor. Forty thousand years from now it’ll swing past that star at roughly 1.7 light-years.
Even at that speed, compared to light it moves like a snail.

It took #Voyager1 49 years, 2 months and 11 days to cover one light-day. Voyager 2 took a different route so it could visit Uranus and Neptune — it won’t reach the same distance until 2035.

November 18 is worth marking: the first human-made object one light-day from Earth.

[Nereide @Nereide]

In this fabulous pic, the #Moon shines over Mount Antelao, San Vito di Cadore 🇮🇹.

The pic was selected by the @RMGreenwich for the “Astronomy photographer of the Year 2015” competition.

Img credit:©Marcella Giulia Pace
➡️https://t.co/2EsyPTmGvn

#Space
#StormHour
#SpaceHour

[Nereide @Nereide]

#WorldScienceDay for Peace and Development.

Science lets us understand the wonderful universe we live in.

It allow us to find answers to emerging challenges so we can create a more just and fair global society.

-----------------------

Image: NGC 2170, Stellar Nursery in Monoceros

Credit: Robert Gendler

Source➡️https://t.co/Pb4XMZt7E7

Via Wikimedia Commons

Creative Commons Attribution 4.0 International License

#ScienceDay #Science

[Nereide @Nereide]

@joyfulmath3 The list is there to show the scale jumping around.

Moon’s only 1.3 light-seconds, Sun’s about 8 minutes, Neptune a bit over 4 hours.

Then suddenly you’re talking light-years and millions of light-years.

A light-day lands right in the middle of that jump, so it feels big.

[Nereide @Nereide]

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#Voyager1 is about to reach a milestone no other human-made object has ever touched: one light-day away from Earth.

On November 18, 2026 at 5:16 EST it will have traveled roughly 26 billion km.

A journey of almost 50 years.

A light-day is just how far light goes in 24 hours.

Light travels around 300,000 km a second, which adds up to roughly 26 billion km in a day.
It’s the clearest way to measure enormous space distances, because nothing goes faster than light.

The Moon is 1.3 light-seconds away. The Sun takes 8 minutes and 20 seconds. Neptune sits a bit past 4 light-hours. Proxima Centauri is the nearest star, 4.24 light-years off. Andromeda is around 2.5 million light-years away.
A light-day is already enormous.

Voyager 1’s doing about 61,000 km/h right now, pointed at Gliese 445 over in Ursa Minor. Forty thousand years from now it’ll swing past that star at roughly 1.7 light-years.
Even at that speed, compared to light it moves like a snail.

It took #Voyager1 49 years, 2 months and 11 days to cover one light-day. Voyager 2 took a different route so it could visit Uranus and Neptune — it won’t reach the same distance until 2035.

November 18 is worth marking: the first human-made object one light-day from Earth.

[Nereide @Nereide]

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Pic by NASA/JPL-Caltech/The University of Iowa

Reference: https://t.co/wTdZSu64Yx

[Nereide @Nereide]

@MucJiu Voyager 2 is on track to be one light-day from Earth in November 2035.

It took a different route after launch so it could visit Uranus and Neptune.

That longer path is why it will hit the same milestone roughly nine years after Voyager 1.

[Nereide @Nereide]

Gliese 445 is an obscure star in Ursa Minor, also listed as AC +79 3888, more than 17 light-years from Earth.

Voyager 1 is expected to pass about 1.7 light-years from it in 40,000 years — the closest approach — and then keep going.

The article notes that even at nearly 38,000 mph this is still a crawl compared with light.

[Nereide @Nereide]

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Pic by NASA/JPL-Caltech/The University of Iowa

Reference: https://t.co/wTdZSu64Yx

[Nereide @Nereide]

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Using #Hubble, a research team has measured with greater precision the distance to the #galaxy NGC 3783, which has a very active #blackhole at its center.

Until now the estimates were more uncertain: we now know it lies about 137 Mly away, with a much smaller uncertainty than before.

To do this the team used Cepheids—stars pulsing regularly, growing brighter then dimmer.

Their peak brightness shows how far away they are.

They found 7 Cepheid candidates (4 strong) in NGC 3783 and compared them with closer stars to calculate the galaxy’s distance.

The result is that NGC 3783 is a bit farther than previously thought, making it one of the most distant galaxies with a Cepheid-based distance measurement.

This means that the center, where the black hole "feeds" on matter, is actually brighter than we believed: about 20% more.

A better knowledge of the distance to NGC 3783 also helps us understand how large the structures around the black hole are.

Previously the sizes were estimated only approximately; now the observed measurements can be translated more reliably into real physical sizes.

In short: a more reliable distance measurement for NGC 3783 helps us understand better how these active galaxies work and how powerful their black holes are.

It is one small additional piece in the map of the nearby universe.

[Nereide @Nereide]

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When the Rosetta probe came home for the last time, it took this photo of Earth from 633,000 km.

A crescent over the South Pole, Antarctica under the polar vortex and those bright spots of sea ice.

It remains one of the most beautiful images of the mission.

It was 12 November 2009, 13:28 CET.
OSIRIS (narrow-angle) combined three shots with orange, green and blue filters.
Resolution 12 km/pixel.
The next day, at 08:45 CET, the third and final Earth swingby at 2,481 km altitude, south of Java.

That pass gave the probe its final boost of 3.6 km/s.

After three Earth flybys and one of Mars, Rosetta finally had the energy to leave the inner Solar System and go meet comet 67P/Churyumov-Gerasimenko in 2014.

During the approach Rosetta was also set to check whether the small velocity anomaly (a few mm/s), seen in some Earth flybys since 1990, would show up again.

[Nereide @Nereide]

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Europe’s TGO orbiter picked up something odd in the Martian atmosphere: spikes of hydrogen chloride right over the fissures on Alba Mons.

Not in winter, when that gas usually shows up, but at the start of northern summer.

It doesn’t match the normal seasonal pattern.

#Mars

[Nereide @Nereide]

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LHCb at #CERN just reported evidence of an extremely rare decay involving a beauty particle.

If it holds up, this would be the rarest beauty decay anyone has ever seen.

It’s the result of a search that’s been going on for decades.

https://t.co/uevw8MkvS3

View of the LHCb experiment (Image: CERN)

[Nereide @Nereide]

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Mars as never seen before: this splendid mosaic was created to mark 20 years of ESA’s Mars Express, launched on 2 June 2003, using data from its High Resolution Stereo Camera (HRSC).

Credits and further reading➡️https://t.co/lGKwnuuqdd

#scritturebrevi #VentagliDiParole

[Hubble @NASAHubble]

Pardon me?

An interacting galaxy pair seen near center is upstaged by several foreground stars that belong to our home galaxy, the Milky Way.

Called IRAS 21101+5810, the galaxy pair resides a whopping 550 million light-years away: https://t.co/OjvYadVDY9

[CMS Experiment CERN @CMSExperiment]

A rare double act: CMS publishes its first search for Higgs boson pair production with two charged leptons and two bottom quarks in the final state using data collected at a centre-of-mass energy of 13.6 TeV, improving the sensitivity of the search.

🔗 https://t.co/vIMvAgrIpm

[Maria Gritsevich @GritsevichMaria]

When your good friend and PhD student takes initiative to observe an interesting target :)

[Leonardo Petrillo @92sciencemusic]

@Nereide This is a great tribute post and, yes, you have undoubtedly achieved the goal set in the conclusion. Today more than ever we need to keep in mind the lessons of brilliant and sensitive minds like Sagan, to counteract the cultural and social regression underway.

[Nereide @Nereide]

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"On that blue dot, that's where everyone you know and everyone you ever heard of, and every human being who ever lived, lived out their lives."

― Carl Sagan, born November 9, 1934

Carl Sagan, in addition to being known for his scientific work as an astronomer and planetary scientist, and for his Science communication activity through the television series "Cosmos", was involved in much more.

For example, in 1985, he testified before the United States Congress on climate change, warning that it was real and man-made, a message that is now recognized as very far-sighted.
Carl Sagan's 1985 speech was a watershed moment in the fight against climate change. Today, his words continue to resonate, reminding us of the urgent need for international cooperation, and to follow science to take action for the well-being of our Earth.

He was involved in popularizing the theory of nuclear winter, proposing that a large-scale nuclear conflict could cause dramatic global cooling, making life on Earth extremely difficult.

In addition to being one of the founders of the SETI project, Sagan was also the creator of the first physical communications sent into space via the Pioneer plaque and the Voyager Golden Record, with the intent of communicating with possible extraterrestrial life forms.

In 1978, he won the Pulitzer Prize for "Dragons of Eden: Speculations on the Evolution of Human Intelligence," a 1977 book in which he combines the fields of anthropology, evolutionary biology, psychology, and computer science to give a perspective on how human intelligence may have evolved.

Sagan was a fervent advocate of skeptical scientific inquiry and the scientific method, encouraging the public to ask critical questions and not to accept extraordinary claims without equally extraordinary evidence.

In his last interviews, he emphasized the importance of science in society and warned of the dangers of a non-scientifically literate population, a message that continues to resonate today.

I hope to have offered an insight into Carl Sagan also as a critical thinker, communicator, and person involved in social and political issues with a strong future impact.

Image credit: NASA

[Nereide @Nereide]

Yes. Most galaxies with Cepheid distances are closer.

NGC 3783 is now one of the farthest galaxies for which this method has worked.

The new value also has a smaller uncertainty than earlier estimates that relied on other techniques, so it improves the overall picture of how far this active galaxy really is.

[Nereide @Nereide]

1/2
Using #Hubble, a research team has measured with greater precision the distance to the #galaxy NGC 3783, which has a very active #blackhole at its center.

Until now the estimates were more uncertain: we now know it lies about 137 Mly away, with a much smaller uncertainty than before.

To do this the team used Cepheids—stars pulsing regularly, growing brighter then dimmer.

Their peak brightness shows how far away they are.

They found 7 Cepheid candidates (4 strong) in NGC 3783 and compared them with closer stars to calculate the galaxy’s distance.

The result is that NGC 3783 is a bit farther than previously thought, making it one of the most distant galaxies with a Cepheid-based distance measurement.

This means that the center, where the black hole "feeds" on matter, is actually brighter than we believed: about 20% more.

A better knowledge of the distance to NGC 3783 also helps us understand how large the structures around the black hole are.

Previously the sizes were estimated only approximately; now the observed measurements can be translated more reliably into real physical sizes.

In short: a more reliable distance measurement for NGC 3783 helps us understand better how these active galaxies work and how powerful their black holes are.

It is one small additional piece in the map of the nearby universe.