Setting of our Sun taken by the Opportunity probe
Incredible sunset taken in November 2010 by the Opportunity probe which has been on the planet Mars since 2004.
The video was reconstructed by sequencing the images taken by the panoramic camera (Pancam) placed by NASA in the Mars Exploration Rover Opportunity.
The video was processed using material from NASA, the American space agency.
THE SOLAR SYSTEM
Sunset on the planet Mars taken by the Spirit probe.
Photography of the Sun made with special telescopes and advanced shooting techniques.
The massive jets of incandescent gas expelled from the star testify to the intense solar activity and the enormous amount of energy it produces and radiates into space.
The Sun is the star located in the center of the Solar System, all the celestial objects that are part of it orbit around it. Comparing the Sun with our planet we quickly realize its grandeur: it is 109 times larger and 333,000 times more massive than the Earth!
According to the common definition, a star is a celestial object that shines with its own light, while wanting to refer to the official definition it is necessary to deepen some aspects related to the processes that take place in the stellar core.
During the formation of the Sun, the intensity of gravity caused pressure and temperature to increase immeasurably in its center (core). Under these conditions, hydrogen, which is the main constituent of stars, spontaneously undergoes reactions called nuclear fusion. Products of these reactions are helium and an enormous amount of energy, which through various processes leaves the nucleus to reach the surface and radiate into space in the form of electromagnetic waves (light and heat) and particles.
Officially, therefore, stars are defined as celestial objects with a spheroidal shape (spheres more or less flattened at the poles) whose nucleus is the site of nuclear fusion reactions.
Currently the Sun is in a stable phase of its evolution, during which energy is produced through the fusion of hydrogen into helium. It is estimated that for stars like ours this phase can last about 10 billion years, which means that the Sun is halfway through its evolution. At the end of this long period of stability, the Sun will enter a phase of strong instability, its size will increase by over 100 times and the closest planets will be incorporated and destroyed, even the Earth will most likely touch this fate. In about 8 billion years the outermost layers of the Sun will be ejected and over the next hundreds of billions of years what remains will cool completely.
This is what the surface of the Sun looks like when seen with special telescopes. The energy diffused by the Sun comes from its core, through various processes it reaches its surface and then radiates into space. The energy flow is neither homogeneous nor constant, therefore there are colder areas of the solar surface, which appear darker and others warmer, which appear lighter.
Close-up image of the solar surface obtained with telescopes equipped with particular and sophisticated filters. The darker (colder) areas are called sunspots. The lighter (hottest) areas are called flares.
The Sun, the Perfect Star
Waiting for a dawn in the making, seated and well covered, on the top of the Monte Ceva, one of the easternmost peaks of the Euganean Hills, facing east, how suddenly everything changes! The veiled solar disk appears on the horizon in the only moments in which it can be seen with the naked eye, as observation passes through multiple layers of our atmosphere. During dawns with the clear sky, from here, it appears above the sea. For many it can be a moment of wonder, ecstatic, in ancient times it was a constant observation to calculate the time of that relative day.
The Sun is the light and heat of the world. The Earth travels in an orbit around the Sun and is at such a distance from it that, due to "fine architecture", it has formed and has maintained life on our planet since time immemorial. As far as we know at present, in no other planet or place in the Solar System has nature given this task: that of making life flourish.While we see the Sun rise, we have to think that it is the only star whose physical characteristics we can optically admire. Man has built precious tools that allow, through the use of appropriate filters that break down its intense light, to be able to observe it in different ways. Only with the help of these tools can we observe it. We can understand the main rule of attention: observing the Sun with the naked eye can seriously damage the retina of our eye. The Sun determines, together with the Moon, the calculation of the daily, monthly and annual time, relative to each latitude.
These attributes, the temporal one and that of spreading life, together with its spreading the light, forced man, in ancient times, to believe him as a divinity. Many kings, emperors, pharaohs or rulers have made believe that their origin descends from the Sun. In any case, our star has been revered and its cult still lives among many peoples of the Earth. Helios, for the ancient Greeks, son of Hyperion and Theia, two Titans, imagined him crossing the sky on a fiery chariot pulled by horses also emitting sacred fire.
An ancient mystery religion, Mithraism, also defined by historians as an astral religion, notes it among the main divinities. Later in ancient Rome, the Sol invictus, the Sun that is reborn from December 25th, identified as the moment in which, after some phase of stationing at the lowest point of the Sky during the Winter Solstice, the Sun begins its ascent. On 21 June 2017, this year's Summer Solstice comes true. The moment when the Sun "touches" the highest point in the sky, it remains stationary (Solstice, from the Latin Sol-sistere: the Sun that stops) for a few days, until June 24, the day when our star gradually begins getting down.
The moment relating to June 24, today St. John, was commemorated by the most ancient pagan populations. From the Celts comes the tradition that on the day relating to June 24 of our calendar, purifying fires were lit that lasted all night and then extinguished by the morning water. Fire and Water, two elements attributed to St. John the Baptist. In these days of the year the festival of the town of Carbonara is held, located on the western side of the Euganean Hills and dedicated to St. John the Baptist.
Image of the Sun in "H-Alfa"
This magnificent image of the Sun was taken by NASA's SOHO (Solar and Heliospheric Observatory) probe, the famous probe that is able to monitor the activity of the Sun with state-of-the-art instrumentation. With this type of observation, called "H-Alpha", also from the Earth, we can observe all the phenomena related to the combustion of the Sun as inside this instrument there is a filter that blocks the electromagnetic waves visible to the human eye, letting them pass only one located in the red band, which identifies the hydrogen gas. A fantastic observation that highlights various phenomena of the Sun: the "Protuberances", that is to say those jets of fiery gas that stand out and then re-enter forming huge slots. The "Filaments" are protuberances observable from the zenith point of view. The phenomenon of "Granulation" is perfectly visible on the "Photosphere", the surface of the Sun. The "Flares" are areas of violent solar eruptions that spring with an energy equal to tens and sometimes hundreds of millions of atomic bombs. With this observation it is also possible to observe “Sunspots”, areas of intense magnetic activity in which the surface temperature is relatively cooler.
How was the sun formed?
To understand it, it is necessary to understand how a star is formed: in the Universe there can be areas filled with various types of gas which in some points can thicken, become like "lumps" around which other gas thickens. Under these conditions their speed and pressure can increase: when, in the core of these densities, the pressure rises, the temperature also rises dramatically and when a limit condition of pressure and temperature occurs, nuclear fusion reactions are triggered which determines the formation of a star.
The most established theory is the one that traces the formation of the Sun after a frightening explosion of a Supernova star, the gases released after that catastrophe have allowed the formation of new stars, including, therefore, our celestial body.. It is on average 150 million km from the Earth and its light reaches us after 8 minutes. Nestled along one of the spiral arms of our galaxy, called the Orion Arm, the Sun is 26 light-years from the center of the Milky Way.
Being our galaxy 100,000 light years long, the Sun is therefore about a third of the distance from its center. The "path" that the Sun makes, during its journey in the Celestial Vault, day after day, is called Eclittica and it is of extraordinary importance to detect it during the observations of the night sky, as it allows to identify the positions of the Moon and the planets. A decisive orientation. Observation, even amateur, of the Sun is possible with various types of optical instruments that technology has made available to our eyes. The telescopes adapted to observe the Sunspots are those for observation in "White or integral light" and are useful for observing these phenomena formed by a large magnetic activity of the Sun and visible as the surface temperature is relatively less hot than that of the Photosphere, that is to say about 4500 degrees K. But an exceptional observation is obtained by pointing an instrument developed to observe only the part of the hydrogen gas of our sun. This way of seeing the Sun is called observation in H-Alpha, with which our eye can verify many phenomena derived from the combustion of the Sun such as protuberances, filaments, granulation and sunspots that give an understanding of the immense combustion of the Sun: a 'energy emission equal to 4 million tons of fuel per second, the same amount of energy that would be useful to the Earth for a whole year.
Sunrise and sunset are visible in many delightful places in the Euganean Hills and are exclusive natural moments, which are never the same day after day and which can change for various reasons due to different weather conditions but above all they are natural, ecstatic, exciting moments. poetic. Also this summer, in this territory, in these moments that we must know how to grasp, the Sun and its light will be magic.
The analemma of the Sun is a single image made up of several frames of the Sun taken at short intervals of a few days but always at the same time over the course of a year. This technique allows us to define that the Sun, in the Sky, makes a "journey" in the shape of the number 8, extended, the shape of continuity. The lowest point corresponds to the Winter Solstice, the highest point to the Summer Solstice. It is extraordinary that, in mathematics, this form is defined as "Infinite".
Astronomical Observatory 'G.V. Schiaparelli '- Campo dei Fiori
Comet C / 2011 L4 (PANSTARRS) was discovered on June 6, 2011 by the American professional observatory PAN-STARRS, acronym for Panoramic Survey Telescope and Rapid Response System. The observatory is located on the top of Haleakala on the island of Maui in Hawaii. At the time of discovery, the comet was of magnitude 19-19.5, at a distance from the Sun of about 8 AU, equal to about 1.2 billion km (between the orbits of Jupiter and Saturn).
In March 2012 its brightness had increased to magnitude about 14, therefore visually observable with telescopes of at least 30cm in diameter under dark skies. It continued to gradually increase until it was observable with the naked eye in February 2013, about a month before the perihelion, which occurred on March 10, 2013 at a distance of 0.30 AU, equal to about 45 million km from the Sun, and an estimated maximum magnitude. between 0 and 1 (the perigee, the closest point to the Earth, occurred 5 days before the perihelion, at a distance of just under 165 million km.
NASA's STEREO probe captured the perihelion phase, as can be seen in the following video:
In the days following perihelion, that is, when the comet began to move away from the Sun, it became visible in our latitudes, although immersed in the evening twilight. On 14 and 15 March, thanks to a respite in the adverse weather conditions at that time, it was possible to observe it with the naked eye at our Observatory thanks to clear skies with north wind (from Varese, due to light pollution, it was not seen to naked eye).
The magnitude was between 1 and 2, although the low height on the western horizon (5 degrees) and the still present twilight (45 minutes after sunset) greatly affected its visibility: it would certainly have been more satisfactory if the comet had been high in the sky.
In any case, for our hemisphere, it was the brightest comet visible after the 1997 Hale-Bopp.
The comet quickly moved northward away from the Sun, managing to be observable well beyond the setting of the Sun, therefore with a sufficiently dark sky. This fact, combined with the progressive change of perspective, showed a wonderful fan tail of powders.
In the following weeks, again thanks to the change of perspective, the ion tail, although very weak, showed itself up to an overall length of about 10 degrees!
From the analysis of the dust and gases produced, it was estimated that the core must have had a diameter of only about 1km.
To date (mid-October 2013) the comet has a visual magnitude of about 13 slowly but surely it will return to the Oort cloud from which it came, and having a hyperbolic orbit it will never return to visit the Solar System.
During the PANSTARRS visibility period, two astronomers from INAF of Trieste, Marco Fulle and Paolo Molaro, asked us to create a high resolution spectrum (in technical jargon it is called "echelle") of the comet, well aware of the potential of the comet. our spectroscope, used for years for a vast observational program in collaboration with the Asiago Astrophysical Observatory.
The results of these scientific observations were recently published in the Astrophysical Journal with an article entitled "Potassium detection and Lithium depletion in Comets C / 2011 L4 (Panstarrs) and C / 1965 S1 (Ikeya-Seky)". Paolo Valisa and the writer, both from the Schiaparelli Observatory of Varese, are the co-authors of the article, which can be downloaded at the following link: http://arxiv.org/abs/1307.4885 (click on "PDF" at the top right of the page).
In summary, the article explains the chemical abundances in the comet's spectrum, which has an overabundance of sodium compared to potassium, a phenomenon explained in the article. What is completely missing is lithium, which instead is present, for example, in meteorites: why in comets (at least in this one) there is no trace of it?
To unravel the mystery, spectra of other comets are needed when they are quite close to the Sun.
Below we propose an excerpt of our most interesting photographs:
PANSTARRS and the Andromeda galaxy - Photograph of 31 March by A. Aletti from Mondonico (VA).
Space: here is the most distant image of the Earth
Our planet imaged beyond Neptune's orbit by the Voyager 1 probe.
It is the farthest image you have of ours world, photographed by the space probe Voyager 1, from a distance of over 6000 million kilometers, beyond the orbit of Neptune. The photo, taken on February 14, 1990, shows the Earth as an almost imperceptible point of light due to the glare of the Sun. The image was selected in 2001 by Space.com, as one of the ten best space science photos in history.
Space: here is the most distant image of the Earth
Voyager 1 is a space probe launched by NASA on September 5, 1977 as part of the Voyager program aimed at studying the external solar system, together with its twin, Voyager 2. A real record that of the aircraft that for 42 years, 2 months is still able to communicate with the Deep Space Network and receive routine commands. At a distance of 147,380 AU from Earth, it is the furthest artificial object from Earth. The spacecraft's goals, achieved over the years, include the flybys of Jupiter, Saturn and the largest moon of Saturn and Titan.
Some meteorites that have fallen to Earth are older than the sun
A recently published research suggests that older material than the system itself has arrived in the Solar System, produced by the explosion of a star "lived" before our Sun.
Michael Bennett, coordinator of the study conducted at the National Superconducting Cyclotron Laboratory at Michigan State University (USA), worked on fragments and dust of meteorites fallen to Earth, noting that some components are older than the matter of the Solar System: their origin is earlier , and must therefore trace back to a star that exploded before the birth of the Sun.
Before the Sun. Some stars, at the end of their life, can originate an explosion that involves their outermost part and thus give life to the "novae", while the "supernovae" are the ones that totally explode. In both cases the energies involved create new elements, heavier than those present (which are mainly hydrogen and helium) and necessary for the formation of the planets.
Maven, the probe has started that will tell us why Mars no longer resembles the Earth
in the picture: Martian sunset captured by the Spirit probe.
The time when Mars was the planet of mystery and extraterrestrial species is over, replaced by research and discoveries that increasingly reveal international competition for understanding the Red Planet. Fantasy, however, continues to fuel the imagination, as evidenced by a recent video depicting Mars as rivers and oceans flowed through it. This is precisely the aspect that Maven (Mars Atmosphere and Volatile EvolutioN), the NASA probe launched yesterday and which will arrive on 22 September 2014 in the orbit of the Red Planet, will have to clarify. With this mission, NASA intends to clarify what process led Mars to become a barren earth in a few years after being so similar to that of our planet.
Curiosity has confirmed the presence of water on Mars, in a past that probably drew a totally different planet from the one we know today. An immense ocean engulfed much of the northern hemisphere, while in the south, rivers flowed richly through those canyons that today contribute to the ghostly image of Mars. 4 billion years ago volcanoes were active and released into the air those gases that are fundamental to the planet's surface warming and pressure build-up. Today, however, the average temperature is -53 ° C, with peaks of -128 ° C, and, above all, with a pressure so low as to vaporize the water (if any) instantly. The thin atmosphere of Mars is now composed of more than 95% carbon dioxide
What caused Mars to lose its blue sky? At the moment only theories can be advanced and the most accredited one shifts attention to the Sun, whose solar storms, in a period of greater activity than the current one, would have moved winds of sufficient strength to sweep away the lighter gases of Mars. leaving the planet unprotected and initiating the cooling and decompression process that would have given the planet its present appearance. The fate of the Earth would have been more fortunate because, despite the greater proximity to the Sun, it is protected by a magnetic field stronger than the Martian one. Hypothesis, that of the solar wind, that Maven will have to confirm or replace, while the whole world runs after NASA threatening to overtake.
A few days later Maven Mars Orbiter will arrive, a probe from the Indian space agency Isro, which will have the task of detecting methane in the atmosphere. Also in 2016 NASA will send InSight to Mars, a probe that will pierce the ground (more than already done) to allow a third level of knowledge after the superficial and atmospheric one. In the same year, the probe of the ExoMars program could also arrive, the result of a collaboration between the European agency ESA and Russia (NASA withdrew its participation), while in 2018 the first European rover equipped with a drill longer than that could land. American InSight. Drill that will be supplied by ASI, the Italian Space Agency.