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A spectacular view of the Andromeda galaxy [Robert Gendler]

The two large spiral galaxies will eventually collide in five billion years or so, according to calculations based on data published in the second release of the Gaia astrometric satellite catalog. But it won’t be a head-on collision

Our galaxy, the Milky Way, together with about seventy other galaxies, is part of a cluster called the Local Group, which extends for about 10 million light-years. The two largest and most massive galaxies of the Local Group are Andromeda (M31) and the Milky Way, followed by another spiral, the Triangle Galaxy (M33). The fourth galaxy of the group by mass and size is the Large Magellanic Cloud, which is considered a minor galaxy, as it is a Milky Way’s satellite.

The glue that holds the Local Group together is the mutual gravitational attraction between the several galaxies that are…


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Dimensions compared between Betelgeuse and the Sun (simulation)

A new study recalculates the main parameters of Betelgeuse based on a triple series of astrophysical simulations. The result is that the red supergiant seems to be a little less gigantic than indicated by previous calculations and a little closer

Betelgeuse, the red supergiant in Orion, has always been one of the most observed and studied stars by astronomers. Despite the nearly 1,500 scientific papers that have been dedicated to it from 1850 to today, it is surprising how much our knowledge of this magnificent star is still inaccurate. In particular, Betelgeuse’s exact distance and radius have been the subject of a long series of estimates, none of which has so far managed to agree once and for all the researchers interested in the question.

A new article, published on 13 October in The Astrophysical Journal, is part of this…


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Is it possible that the moons orbiting a planet have moons in their turn? Theoretically, yes, but only in special cases. A study addresses the issue in detail, putting forward some suggestive hypotheses

One evening, before going to bed, Levi, a four-year-old kid, asked his mother one of those questions that adults can’t answer, questions that spring spontaneously from the unbridled imagination of children of that age:

“Mom, can moons have moons?”


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Artist’s impression of a binary system consisting of a blue supergiant and a black hole (right). The black hole’s gravity pulls matter away from its binary companion, generating a stream that is deposited on the accretion disk orbiting the black hole. The X-ray emission observed in the binary system M51-ULS-1, located in the galaxy Messier 51, originates from the infall of matter towards a black hole or a neutron star [ESA/Hubble, M. Kornmesser, L. L. Christensen]

Creatively using archival data from Chandra and XMM-Newton X-ray space telescopes, a group of researchers detected the transit of a planet in a binary system consisting of a blue supergiant and a neutron star (or black hole). All this in M51, the Whirlpool Galaxy, located 28 million light-years away from us

Are there extragalactic planets?

Until the 1990s, the only known planets were those of the Solar System. Astronomers were pretty sure that other stars have planetary systems, too, but they had no proof. The existence of planets orbiting stars other than the Sun remained a simple possibility, a probable but not proven fact. Then, in the mid-90s, starting with the discovery of 51 Pegasi b, a real flood of exoplanets came to fill the gap of knowledge that has accompanied humanity since the dawn of time. In just a quarter of a century, as many as 4,284 planets were found orbiting Milky Way stars.


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CGI image of the solar-powered aircraft that the Northrop Grumman group developed as a concept for a future, hypothetical mission to explore the atmosphere of Venus [Northrop Grumman Corp.]

A study published in “Nature Astronomy” reports the discovery of phosphine in the clouds of Venus, a compound that on Earth is exclusively associated with biological processes. This makes it plausible that microbial life forms exist floating in those clouds. To verify the hypothesis, it would be necessary to send to Venus a probe different from all the previous ones: An aircraft able to fly among the Venusian clouds, analyzing their composition on site

The phosphine that shouldn’t be there

A chemical compound, previously known only to experts, experienced a sudden moment of fame for several days. It is phosphine, made up of one phosphorus atom and three hydrogen atoms (chemical formula PH₃). The reason for its unexpected popularity lies in the fact that a study published in Nature Astronomy on September 14 announced that convincing evidence of its presence was found among the cloud decks that perpetually cover Venus’s surface.

The phosphine’s spectral signature was identified through observations made with the James Clerk Maxwell Telescope in 2017 and with the ALMA interferometer in 2019. The observed region of the…


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Artist’s impression of ESA’s Gaia satellite [ESA–D. Ducros, 2013]

A step-by-step guide to understanding how measuring a tiny angle can give us the key to knowing stellar distances

How far away are the stars? Human beings have been asking themselves that question since the dawn of time. Philosophers and astronomers of antiquity imagined that those luminous dots visible in the night sky, some brighter, others dimmer, were very distant worlds, somehow similar to the Sun or the Earth. But how to measure their distance?

In fact, a brilliant, theoretically correct method was devised over two millennia ago. Aristarchus of Samos, an astronomer who lived between the third and second centuries BC, had understood that it is possible to use the properties of right triangles to derive the Sun’s…


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An artistic representation of the PSR J1023 +0038 binary system. The pulsar, not visible in the image, is surrounded by its luminous magnetosphere, from which two radiation beams (in green) emanate, emitted in opposite directions. The binary companion, visible on the left, has acquired an oblate shape due to the pulsar’s gravitational attraction. A stream of matter moves from the binary companion towards the pulsar, where it will gradually form an accretion disk. Other matter, coming from the companion star irradiated by the pulsar, is lost in space [NASA Goddard’s Scientific Visualization Studio]

Is it possible to discover an asymmetry of a few thousandths of a millimeter on a neutron star 42 million billion km from Earth? Incredible as it may seem, it is possible. An Indian astrophysicist did it, using the available observational data elegantly and creatively

A millisecond pulsar

In the direction of the small constellation Sextans (the Sextant), straddling the celestial equator, there is a binary system consisting of a millisecond pulsar called PSR J1023 +0038 and a companion star classified with the spectral type G6. This system has been the subject of many studies in the last two decades due to its rare characteristics. PSR J1023 +0038 is, in fact, one of only three pulsars currently known to have been observed in two distinct states: the normal one, so to speak, in which its pulsation is clearly distinguishable in radio waves, and the accretion state, in which…


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Artist’s impression of the Qingjiang biota [Z. H. Yao / D. J. Fu]

An extraordinary fossil deposit discovered in the Chinese site of Qingjiang allows us to observe, as in a photograph, the wide variety of life forms that populated the shallow waters of a Cambrian sea

For over three billion years, life on Earth existed only in the form of single-celled organisms. Then, around 600 million years ago, unequivocal fossil traces, found in many parts of the world, testify to a vast and sudden spreading of multicellular life during the Precambrian. It is the Ediacaran biota. Very strange-looking life forms spread in the shallow coastal seabed, originating a bizarre fauna, which paleontologists consider
a kind of global experiment in multicellular life, driven by natural selection to find the most suitable body shapes and structures for survival.

Within a few million years, and for reasons we do…


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Artistic representation of the Milky Way, in which the constituent elements of the galaxy are represented: the central bulge, the galactic disk, the globular clusters, and a vast outer halo, less dense than the disk, formed by a scattered population of very ancient stars [NASA, ESA A. Feild (STScI)]

It is the total mass of the Milky Way, based on observations from the Hubble and Gaia space telescopes

Despite decades of research, the mass of the Milky Way is rather roughly known. Among the reasons that complicate the calculation of this fundamental value is the fact that the solar system is right in the middle of the galactic disk. Therefore, we lack the perspective from which to get an exact overview of our galaxy and accurately measure its total extent.

But astronomers do not lose heart and use what they have available. One of the methods used to estimate the mass of the Milky Way is the kinematic method. It is based on the motion of objects gravitationally…


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[Stefan Keller / Pixabay]

How to use solar radiation to push ultra-light probes up to 2.3% of light speed

Since the discovery of Proxima b in 2016, several exoplanets with exciting characteristics have been identified within a few light-years of the Earth. So it has become more urgent to develop some propulsion system calibrated for interstellar distances, allowing uncrewed probes to reach for the nearest stars within a reasonable time, that is, within decades rather than centuries or millennia.

Reaching for the stars: a very difficult undertaking

Unfortunately, the undertaking is by no means easy. The only space missions that have developed a velocity sufficient to escape the gravitational pull of the Sun (Pioneer 10 and 11, Voyager 1 and 2, New Horizons), are all based on…

Amazing Science

Astronomy, Cosmology, Astrobiology, Space Exploration…

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