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Is Venus really the closest planet to Earth ?

Image Credit: NASA
An artist’s impression of the planets in our solar system.

In a new study, scientists have worked out that, on average, Mercury is actually closer to us than Venus.

The order of the planets in our solar system is one of the most fundamental facts in astronomy – from the Sun we have Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and then finally Neptune.

Now though, a trio of scientists has called this well-established ordering in to question by claiming that Mercury – not Venus – is the Earth’s closest neighbor. But can this really be true ?

The key to this idea lies in looking at the average distance between each planet and the Earth as they orbit the sun. While Venus undoubtedly strays closer to the Earth than Mercury at its nearest point, it also strays a lot further from the Earth when it is at the opposite side of its orbit.

By calculating and adding up the average distances at each stage of the planets’ orbits, it turns out that Mercury is actually closer to the Earth on average than Venus.

What’s even more mind-boggling about this is that, based on the same logic, Mercury is actually the nearest neighbor of all the planets in the solar system.

A video explaining the science behind this in more detail can be viewed below.


Source: Physics Today

Space

A colossal flash has occurred on a tiny star

A celestial body, which barely has enough mass to be called a star, suddenly erupted in a flash of incredible power. Astronomers wonder how this is possible.

The discovery is described in a scientific article published in the journal Astronomy & Astrophysics.

Star J0331-27 is located 783 light years from Earth. It belongs to the spectral class L – the class of very small and very cold luminaries, which barely had enough mass to start thermonuclear reactions in their depths. The mass of J0331-27 is only 8% of the sun, and the surface temperature is only 1800 degrees Celsius (compared to 5500 degrees on the Sun).

There is a rule: the smaller the star, the more powerful the outbreaks occurring on it. So, the red dwarfs of class M can boast of real cosmic cataclysms that call into question the suitability of their planets for life. But astronomers did not expect that this pattern applies even to extremely cold L-stars.

According to experts, the flare is due to a sharp restructuring of the magnetic field structure in a small area of ​​the star’s surface. In this case, the energy stored in the magnetic lines is released and heats the surrounding substance. The magnetic field itself is created by plasma – a hot gas consisting of charged particles. Previously, experts believed that the surface plasma of L-dwarfs is too cold to generate a field capable of powerful “fireworks”.

Processing the data of the XMM-Newton space x-ray telescope, the authors found a flash recorded on July 5, 2008. It lasted a few minutes. During this time, 2 ”” 1033 erg of energy was released in the X-ray range alone. This is ten times the energy of the largest flares on the Sun and only half the total energy released by our star in a second (!).

Scientists call events of this magnitude superflares. They are common with the hotter M class red dwarfs, but not with the cooler L stars.

“This is the most interesting scientific part of the discovery, because we did not expect the stars [from the class] of L-dwarfs to store enough energy in their magnetic fields to cause such flashes,” admits Beate Stelzer of the University of Tübingen .

The discovery was made thanks to the XMM-Newton X-ray telescope.
Illustration from esa.int

Prior to this, superflares in L-dwarfs were detected several times in visible light. However, for the first time such an event was recorded in x-rays. Moreover, J0331-27 in general became just the second L-dwarf, from which terrestrial telescopes generally caught x-ray radiation.

After analyzing the data of other observatories, the authors found the optical radiation of this outbreak. But observing it in the x-ray range is extremely important. The fact is that visible light comes from the surface of the body, and x-rays from its atmosphere. This will help astronomers figure out how such a phenomenon nevertheless became possible.

“This is a good question,” says Stelzer. “We just don’t know [the answer]. Nobody knows.”

Riddles don’t end there. The fact is that in all known stars faint flashes occur much more often than strong ones. However, XMM-Newton observed J0331-27 for a total of about 40 days and during this time did not detect any other flashes, although the sensitivity of the instrument made it possible to notice them.

It seems that the magnetic field of the L-dwarf gradually accumulates energy and at once releases it in one powerful cataclysm. This behavior is completely unusual for stars, and now astrophysicists have to deal with new facts.

New X-ray flares on L stars can help with this if they are detected. Stelzer and colleagues made their discovery by processing the XMM-Newton observation archive. It includes information on 400 thousand variable sources discovered by the telescope in 13 years. Not all data has been processed yet, so new surprises may well await scientists.

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Space

Unusual signals come from the GJ 1151 system

Most likely, radio emission is created by the interaction of a planet the size of the Earth with the strong magnetic fields of its star.

Using the LOFAR low-frequency radio telescope, astronomers recorded unusual radio emission coming from the red dwarf GJ 1151, which is located at a distance of about 28 light-years from Earth, these signals, according to scientists, contain evidence of the auroras created by the interaction of the planet with the strongest magnetic fields of the star. The results of the study are presented in the journal Nature Astronomy.

“Radio emission from the interaction of a star and a planet was predicted more than thirty years ago, but only now we were able to identify its signature in the data. Success achieved paves the way for a new way to detect exoplanets in the habitable zone and study their surroundings, ”the authors of the study say.

Red dwarfs are the most common type of star in the Milky Way. They are much smaller and colder than the Sun and have extremely strong magnetic fields. This means that any potentially inhabited planet in the system of such a star, due to its proximity to it, is subjected to intense magnetic activity, which can heat it and even destroy the atmosphere. The radio emission associated with this process is one of the few tools available to evaluate this effect.

“The movement of the planet through the strong magnetic field of the red dwarf acts like an electric motor. This process generates a huge current that provokes radiance and creates radio emission, ”explained Harish Vedantam, lead author of the study from the Netherlands Institute of Radio Astronomy.

In the solar system, similar currents are not generated due to the weak magnetic field of the sun and the large distance to the planets. However, the interaction of the Io satellite with the magnetic field of Jupiter also creates a fairly bright radio emission, at low frequencies superior to the sun.

“We adapted our knowledge from decades of radio observations of Jupiter to the data on the star GJ 1151. For many years it was predicted that the Jupiter-Io system should exist in a larger version of the star-planet, and the radiation recorded by us from GJ 1151 is very well consistent with theory. Today we know that almost every red dwarf contains terrestrial planets, so there must be other stars showing such radiation,” Joe Cullingham added, the co-author of a study from the Netherlands Institute of Radio Astronomy.

Astronomers note that the sensitivity of modern instruments should allow them to find about a hundred more of such systems in the solar vicinity, and, more importantly, assess the conditions in which exoplanets reside in them.

“The main goal is to determine what effect the magnetic activity of a star has on the habitability of an exoplanet, and radio emission is the most important link in this puzzle,” Harish Vedantam concluded.

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Space

Mankind may face deadly viruses in search of new life in space

Professor Dov Greenbaum hypothesized that humanity’s search for signs of life outside the Earth could lead to an even greater threat of infection than a new kind of coronavirus.

In his material, the scientist notes that in the era of human mobility, new viruses spread very quickly, while bacteria grown in outer space can become even more deadly.

For a more detailed study of this issue, samples of genetically engineered bacteria samples are sent aboard the ISS. Despite the fact that the spread of extraterrestrial viruses in real life is considered a very unlikely scenario, the scientist warns against excessive optimism. The astrobiologist claims that dangerous viruses and infections can live in space on rocks that seem dead to the surface. In connection with these, Greenbaum believes that in the case of the reality of the existence of extraterrestrial life forms, their search without appropriate precautions “can lead to infections that will be even more dangerous and deadly than the acclaimed coronavirus.”

The professor also recalled that life was found in those places that were previously considered impossible for the existence of living organisms. So, NASA is going to deliver stones from the surface of Mars, and the Japanese space mission is already returning from the asteroid Ryugu with samples of its rock. At the end of this year, the Japanese Hayabusa2 will reach Earth. According to Greenbaum, it is likely that one of these missions will deliver a fundamentally new type of space infections to Earth.

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