(April 16, 2016)
In this paper, we focus on the effects of stellar rotation on the evolution of the planetary orbit and on the impact of the changes of the planetary orbit on the rotation of the star.
Archiv: Gravitation / Rotation (Weltraumobjekte) / gravity / rotation (space objects)
NASA Shows Einstein Was Right: Our Sun Is Losing Mass – and Its Grip on Our Solar System
(January 19, 2018)
As our sun gets older, it‘s losing mass, and so its gravitational pull becomes weaker. As a result, the orbits of all the planets in our solar system are expanding, not unlike „the waistband of a couch potato in midlife,“ according to a new NASA press statement.
A team of researchers from the Massachusetts Institute of Technology, the University of Maryland and the NASA Goddard Space Flight Center has shown that the aging sun is behaving according to Albert Einstein‘s theory of general relativity.
Like humans, our Sun loses mass as it ages, weakening its gravitational pull. To study the dynamics of our aging star, @NASASun researchers have enlisted Mercury, the smallest, innermost planet in the solar system.
(January 19, 2018)
To study the dynamics of our aging star, @NASASun researchers have enlisted Mercury, the smallest, innermost planet in the solar system. See how: go.nasa.gov/2DsuhTT
Leap second
A leap second (sometimes called intercalary second)[1] is a one-second adjustment occasionally applied to Coordinated Universal Time (UTC), to accommodate the difference between International Atomic Time (TAI), as measured precisely by atomic clocks, and observed solar time (UT1), which varies due to irregularities and long-term slowdown in the Earth‘s rotation.
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After 1972, both clocks have been ticking in SI seconds, so the difference between their displays at any time is 10 seconds plus the total number of leap seconds that have been applied to UTC as of that time; as of 2024, 27 leap seconds have been applied to UTC, so the difference is 10 + 27 = 37 seconds. The most recent leap second was on December 31, 2016.
Schaltsekunde
Die Erde rotiert minimal langsamer, als bei der Definition der Sekunde zugrunde gelegt wurde; ein tatsÀchlicher mittlerer Sonnentag dauert daher um Sekundenbruchteile lÀnger als 86.400 Sekunden.
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Im Jahr 1972 betrug die Differenz zwischen UTC und TAI vor EinfĂŒhrung der Schaltsekunde bereits 10 Sekunden, heute liegt sie bei 37 Sekunden.
Earthâs Rotation Is Slowing Faster Than In 3.6 Million Years
(June 7, 2026)
Earthâs rotation is gradually slowing as climate change melts glaciers and polar ice sheets, redistributing water across the planet and subtly lengthening the day. According to new research from the University of Vienna and ETH ZĂŒrich, the current increase in day length â 1.33 milliseconds per century â is unprecedented over at least the past 3.6 million years. Itâs a new measure of how profoundly human-driven warming is affecting the Earth system, even as only 48% of Americans believe climate change is the result of human activity.
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Researchers reconstructed changes in day length over the past 3.6 million years using fossil remains of benthic foraminifera â single-celled marine microorganisms on the seafloor â and advanced machine-learning techniques.
What Astrophysics Has Taught Me About Changing the World
None of us is helpless. Our actionsâas well as the actions we donât takeâmake a real, tangible impact. So, ask yourself: in which direction will you push the world today?
Ocean Tides and Magnetic Fields
(December 30, 2016)
Earthâs magnetic field is built up from many contributing sources ranging from the planetâs core to the magnetosphere in space. Untangling and identifying the different sources allows geomagnetic scientists to gather information about the individual processes that combine to create the full field.
One contributor is the ocean. But how do the tides affect Earthâs magnetic field? Seawater is an electrical conductor, and therefore interacts with the magnetic field. As the tides cycle around the ocean basins, the ocean water essentially tries to pull the geomagnetic field lines along. Because the salty water is a good, but not great, conductor, the interaction is relatively weak. The strongest component is from the regular lunar tide that happens about twice per day (actually 12.42 hours).
Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland
(24 April 2024)
The preservation of a temperate climate and liquid water on early Earth depends critically upon the strength of the magnetosphere (Sterenborg et al., 2011; Tarduno et al., 2014). Recent atmospheric escape models have suggested that both weak (<10 ÎŒT) and strong (>1 mT) magnetic fields could substantially enhance atmospheric escape under present-day solar wind conditions via the polar wind or cusp escape, respectively (Gronoff et al., 2020; Gunell et al., 2018; Lundin et al., 2007). During the Archean, the Sun was rotating faster, generating a stronger stellar dynamo and therefore the solar wind was more intense than today (Vidotto, 2021). An increased solar wind strength causes greater interaction with the upper atmosphere and greater escape of ions assuming a constant level of protection from Earth‘s magnetosphere. Previous magnetohydrodynamic simulations have suggested that if Earth‘s magnetic field was half its present day strength 3.5 Ga ago, the area of the polar cap (the area containing open dipolar magnetic field lines, allowing atmospheric escape via the polar wind) could increase by up to 50% (Sterenborg et al., 2011).
Giant gravitational waves: why scientists are so excited
On 29 June, four separate teams of scientists made an announcement1â4 that promises to shake up astrophysics: they had seen strong hints of very long gravitational waves warping the Galaxy.
Gravitational waves are ripples in the fabric of space-time that are generated when large masses accelerate. They were first detected in 2015, but the latest evidence hints at âmonsterâ ripples with wavelengths of 0.3 parsecs (1 light year) or more; the waves detected until now have wavelengths of tens to hundreds of kilometres.
Here Nature reports what these monster gravitational waves could mean for our understanding of the cosmos, and how the field could evolve.
The Cosmos Is Thrumming With Gravitational Waves, Astronomers Find
(June 28, 2023)
The scientists strongly suspect that these gravitational waves are the collective echo of pairs of supermassive black holes â thousands of them, some as massive as a billion suns, sitting at the hearts of ancient galaxies up to 10 billion light-years away â as they slowly merge and generate ripples in space-time.
âI like to think of it as a choir, or an orchestra,â said Xavier Siemens, a physicist at Oregon State University who is part of the North American Nanohertz Observatory for Gravitational Waves, or NANOGrav, collaboration, which led the effort. Each pair of supermassive black holes is generating a different note, Dr. Siemens said, âand what weâre receiving is the sum of all those signals at once.â
Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I
(Published 29 June 2023)
Observing and timing a group of millisecond pulsars with high rotational stability enables the direct detection of gravitational waves (GWs). The GW signals can be identified from the spatial correlations encoded in the times-of-arrival of widely spaced pulsar-pairs. The Chinese Pulsar Timing Array (CPTA) is a collaboration aiming at the direct GW detection with observations carried out using Chinese radio telescopes. This short article serves as a „table of contents“ for a forthcoming series of papers related to the CPTA Data Release 1 (CPTA DR1) which uses observations from the Five-hundred-meter Aperture Spherical radio Telescope. (…)
A Pulsar Timing Array (PTA; Foster & Backer 1990) is an array of pulsars, which are regularly observed. The times-of-arrival (TOAs) are measured for pulses that we see beams of electromagnetic waves emitted by the pulsars sweeping over the Earth. As the directions of the radiation beam and the pulsar rotational axis do not coincide, we observe this radiation as regular pulses synchronized to the pulsar rotation (Gold 1969).
Everything you thought you knew about gravity is wrong
(02.08.2019)
We donât know what gravity is.
Say that to the average person, and the answer youâll probably get is some version of: âWhat are you talking about? Gravity is the force of attraction that makes things fall straight down.â But say it to a physicist, and the answer youâll get is, âThatâs right.â
I know, because those are the two answers Iâve been getting for the past few years, ever since I figured out that nobody knows what gravity is, and that just about nobody knows that nobody knows what gravity is. The exception is physicists: They know that nobody knows what gravity is, because they know that they donât know what gravity is.
About the nature of gravitational and gravity waves
(March 20, 2018)
Gravitational waves, which Albert Einstein predicted in 1916.2 were a riddle until 14 September 2015. Gravitational waves are small deformations of the four dimensional spaceâtime geometry. They propagate with the speed of light and they are generated by catastrophic events in the Universe, in which strong gravitational fields and sudden acceleration (or deceleration) of asymmetric distribution of large masses are involved. In the other words, according to the theory of relativity, any accelerating or decelerating massive object that isnât spherically or cylindrically symmetrical generates detectable gravitational waves. That object could be for example neutron star or black hole binary system. Gravitational waves are also produced by cosmological explosions such as supernova. Gravity is the weakest of the four fundamental forces, it is known for a very long time, but still there is no a good unique gravity force (field) theory.
Interplay Between Magnetic Force and Gravity in Massive Star Formation
(September 26, 2021)
The magnetic field is part of one of the four fundamental forces in nature. It plays a vital role in everyday life, from producing electricity in hydroelectric power plants to diagnosing diseases in medicine. Historically, the Earthâs magnetic field served as a compass for travelers before modern technology was available. Crucially for life, the Earthâs magnetic field acts as a shield protecting us from charged particles emanating from the Sun, which are accelerated by the Sunâs magnetic field. Removing this shield would very likely extinguish life on Earth.
Ancient shell shows days were half-hour shorter 70 million years ago
(March 9, 2020)
The length of a year has been constant over Earth‘s history, because Earth‘s orbit around the Sun does not change.
Measuring the irregularities of the Earth‘s rotation
The variability of the earth-rotation vector relative to the body of the planet or in inertial space is caused by the gravitational torque exerted by the Moon, Sun and planets, displacements of matter in different parts of the planet and other excitation mechanisms.
NASA Team Studies Middle-aged Sun by Tracking Motion of Mercury
(18.01.2018)
Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sunâs gravitational grip gradually weakens as our star ages and loses mass.
Earth Is Drifting Away From The Sun, And So Are All The Planets
(Jan 3, 2019)
Deep inside the Sun, the process of nuclear fusion occurs. Every second, the Sun emits some 3.846 Ă 1026 joules of energy, which are released via the conversion of mass into energy in the core. Einstein‘s E = mc2 is the root cause, nuclear fusion is the process, and the continuous emission of energy from the Sun is the result. This energy is the underlying process that powers practically every biologically interesting process occurring on Earth.
Everything you thought you knew about gravity is wrong
(02.08.2019)
âWhat are you talking about? Gravity is the force of attraction that makes things fall straight down.â But say it to a physicist, and the answer youâll get is, âThatâs right.â
I know, because those are the two answers Iâve been getting for the past few years, ever since I figured out that nobody knows what gravity is, and that just about nobody knows that nobody knows what gravity is. The exception is physicists: They know that nobody knows what gravity is, because they know that they donât know what gravity is.
In Earth‘s early history, a day was 23.5 hours and a year lasted 372 days
(13.03.2020)
We‘ve long known that an Earth day lasts 24 hours, and that remains constant because Earth‘s trip around the sun doesn‘t vary.
However, the number of days that make an Earth year have shifted and shortened because days have grown longer. That is thanks to the moon‘s gravity, which draws on ocean‘s tides and slows Earth‘s rate of rotation.
Eine Schaltsekunde mehr Zeit
(30.12.2008)
Wie unregelmĂ€Ăig sich die Erde dreht, sieht man daran, dass zwischen 1999 und 2006 sieben Jahre vergehen mussten, bis eine Schaltsekunde nötig wurde; diesmal sind es nur drei Jahre.
NASA Shows Einstein Was Right: Our Sun Is Losing Mass – and Its Grip on Our Solar System
(19.01.2018)
As our sun gets older, it‘s losing mass, and so its gravitational pull becomes weaker. As a result, the orbits of all the planets in our solar system are expanding, not unlike „the waistband of a couch potato in midlife,“ according to a new NASA press statement.
A team of researchers from the Massachusetts Institute of Technology, the University of Maryland and the NASA Goddard Space Flight Center has shown that the aging sun is behaving according to Albert Einstein‘s theory of general relativity.
NASA Team Studies Middle-aged Sun by Tracking Motion of Mercury
(18.01.2018)
Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sunâs gravitational grip gradually weakens as our star ages and loses mass.
The Orbits Of All The Planets In Our Solar System Are Expanding As The Sun Gets Older, Study On Mercuryâs Orbit Reveals
(25.01.2018)
âMercury is the perfect test object for these experiments because it is so sensitive to the gravitational effect and activity of the Sun,â explained Antonio Genova, the lead author of the study and a MIT researcher working at NASAâs Goddard Space Flight Center.
Researchers were able to make these calculations from the data gathered by NASAâs MESSENGER spacecraft which made three âflybysâ of Mercury in 2008 and 2009 and orbited Mercury between March 2011 and April 2015 before it crashed into Mercury in 2015, Mail noted.
Solar Rotation Effects on The Thermospheres of Mars and Earth
(June 2, 2006)
The first thing that must be understood in this paper is the chain of events that is being tracked. From the Sun‘s rotational quirks, to their effects on CO2 in the respective atmospheres of Mars and Earth. There is also a comparison to older, normalized data from Venus.
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Interestingly, once the data was compiled, there was no correlation found between the levels of CO2 found in the upper atmosphere (~150km on Earth, where this transformation takes place.) Broadening their search, the authors found a strong correlation between the ratio of CO2/O2 and the thermal changes. They feel this suggests that the thermal diffusion effect relies on some form of resonance between the two molecules involved