Planets don't have Moons.

Mercury and Venus are the first and second planet from the Sun. Mercury is the planet which is close to Sun, but the hotter planet is Venus. It is because , the planet has high gas content which makes it too hotter than Mercury. The two planets do not have Moons.

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Asteroid Barely Missed the Earth

 An Asteroid Just Barely Missed Earth, Flying Closer Than   the Moon

                       An asteroid between 16 and 34 meters in diameter (36 and 112 feet) flew by the Earth this morning, about twice as close to our home planet as the moon. The asteroid, named 2017 AG13, was only discovered on Saturday, January 7, by the Catalina Sky Survey, according to space and weather publication The Watchers. It made it's closest approach at about 7:50 a.m. EST, according to JPL data.

If 2017 AG13 had slammed into the Earth, it likely would have been similar to the Chelyabinsk meteor that entered Earth's atmosphere over Russia in February 2013, which was estimated at about 20 meters (66 feet) in diameter. A meteor of that size will mostly burn up in the atmosphere, but depending on the angle of entry, a significant amount of burning hot debris can make it through, possibly destroying property and injuring people as the Chelyabinsk meteor did. The blast of such a meteor burning up would be about 30 times as powerful as the atomic bomb dropped at Hiroshima, but at a distance of roughly 10 miles high, people on the ground would be mostly safe.

Still, not knowing about near-Earth objects (NEO) until days before they fly close to the Earth is slightly concerning. NASA understandably focuses on larger NEOs, ones closer to 140 meters (460 feet) in diameter that could cause catastrophic, life-threatening impacts if we didn't see them coming. We are inevitably going to miss some the size of 2017 AG13, which flew 0.00139 AU from Earth, about 129,000 miles, or 54 percent of the distance to the moon, according to JPL data. But on October 31, 2015, an asteroid 470 meters in diameter (1,500 feet) flew by the Earth just barely beyond the orbit of the moon, and we only knew about it 21 days beforehand. If a 15,000-foot asteroid slams into the Earth, the loss of life would be cataclysmic.

If we detect a large NEO well in advance—months or preferably years before it reaches us—then we could likely find a way to redirect its trajectory so it misses the planet. We could slam an impactor into an asteroid to change its course while it's still far away or, in a last-ditch scenario, hit it with with a nuke. But unfortunately for NEO-hunters, NASA just picked two new space missions as part of its Discovery program, and neither were the Near-Earth Object Camera (NEOCam), a proposed space telescope that would detect ten times as many large NEOs (bigger than 140 meters) than any sky survey before.

These close brushes with asteroids are more common than you might think. At least 35 more NEOs are going to fly closer to Earth than the moon this month alone, according to JPL. The last time NASA missed one, a 15-to-30-meter (50-to-100-foot) asteroid that they discovered only hours before closest approach, was just this past August.

Congress has tasked NASA with discovering 90 percent of potentially hazardous NEOs over 140 meters by 2020, but the agency is nowhere near that goal. And after passing on the NEOCam, it's hard to say when NASA will devote significant resources to finding more NEOs.

The big one is coming. The question is, will we find it in time?

Source: JPL via Business Insider

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Explosion of two star would create a super-bright nova.

  Astronomer Predicts Two Stars Will Collide, Changing the   Night Sky

 

                                               A few years ago, Larry Molnar, a professor at Calvin College, made a bold prediction: what appeared to be a pulsing star, KIC 9832227, was in fact two stars, rapidly orbiting each other on a collision course. It was a far fetched explanation, but after extensive research, Molnar felt confident enough to predict that the two stars would crash into each other around the year 2022, creating a super-bright explosion that will for a brief time outshine most other stars in the galaxy.

Molnar's student Daniel Van Noord was instrumental in coming to this conclusion.

"He looked at how the color of the star correlated with brightness and determined it was definitely a binary," Molnar said in a Calvin College article. "In fact, he discovered it was actually a contact binary, in which the two stars share a common atmosphere, like two peanuts sharing a single shell."

When these stars crash into each other, they'll die, and in doing so release a massive amount of light and energy known as a red nova, increasing the star's brightness by ten thousand times. At that time, it will be visible as part of the constellation Cygnus and the Northern Cross star pattern.

"If Larry's prediction is correct, his project will demonstrate for the first time that astronomers can catch certain binary stars in the act of dying, and that they can track the last few years of a stellar death spiral up to the point of final, dramatic explosion," Matt Walhout, dean for research and scholarship at Calvin College said in the article.

"The project is significant not only because of the scientific results, but also because it is likely to capture the imagination of people on the street," Walhout added. "If the prediction is correct, then for the first time in history, parents will be able to point to a dark spot in the sky and say, 'Watch, kids, there's a star hiding in there, but soon it's going to light up.'"

Source: Calvin College

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Earth's Moon Formed in 'Moonlet' Mash-Up After Many Earth Impacts

An artistic depiction of a collision between two planetary bodies that will form a new moon, while a pre-existing moon already orbits the proto-Earth

 

Credit: Hagai Perets; real images of Mars and Ganymede and an artist’s image of a planet courtesy of NASA were used in the picture construction.

 

 

Earth's moon may be the product of many small moonlets that merged after multiple objects as big as Mars collided with Earth, leaving disks of planetary debris orbiting the planet, a new study suggests.
This idea that multiple impacts led to the moon's birth challenges the most prevalent theory of lunar formation, which suggests that one giant impact led to the formation of the moon.

The new, multiple-impact hypothesis suggests that about 20 moon- to Mars-size objects struck the Earth, flinging debris from the planet into orbit. There, the debris formed disks around the Earth that looked somewhat like Saturn's rings. Over centuries, debris in several disks accreted to form moonlets that migrated farther and farther from the Earth due to tidal interactions. Eventually, the moonlets settled at a distance known as the Hill radius, coalescing to form one big moon.

 

This process isn't too far off from the "Giant Impact Hypothesis," which states that a planet-size rock named Theia struck the Earth, leaving behind a jet of debris that went on to form the moon. But there's one problem with this theory: it doesn't provide a good explanation for the strong similarity between the composition of the moon and the Earth.

"The multiple-impact scenario is a more natural way of explaining the formation of the moon," Raluca Rufu, a researcher at the Weizmann Institute of Science in Israel and lead author of the study, told Space.com. "In the early stages of the solar system, impacts were very abundant; therefore, it is more natural that several common impactors formed the moon, rather than one special one.

In a giant impact scenario, the object that struck the Earth would have needed an Earth-like composition to create a moon that is made of the same materials as Earth. If the impactor were composed of different stuff than Earth, the moon would not be so Earth-like in composition. 

Authors of the new study, which was published today (Jan. 9) in the journal Nature Geoscience, performed several numerical simulations of moon-forming processes and determined that a multiple-impact scenario better explains the moon's Earthly composition.

"Moreover, the composition similarity between the Earth and the moon in the giant impact cannot be explained without using a special Earth-like impactor," Rufu added. "However, if multiple of bodies contribute to the final moon, their chemical signatures can even out, therefore the traces of the various impacts will be masked."

Rufu also said that no existing evidence points more strongly to a single-impact hypothesis, though some studies have found that it is possible to reproduce the moon's composition with a single impact if it strikes with enough angular momentum. Such an impact "will excavate more Earth material; hence the final moon composition is similar to Earth," she said. "After the impact, the Earth-moon system has to lose the excess angular momentum."

"To match both compositional and angular momentum constraints, the single giant-impact hypothesis requires such a specific type of collision that the moon's formation becomes an uncomfortably improbable coincidence," Gareth Collins, a planetary scientist at Imperial College London who studies impacts throughout the solar system, wrote in an accompanying Nature News article. Collins wrote that the study revives "the hitherto largely discarded scenario that a series of smaller and more common impacts, rather than a single giant punch, formed the moon."

Rufu and her colleagues are not the first to propose a multiple-impact scenario. Another paper published in 1989 raised that possibility, but "no further work was done on the subject," Rufu said. "This paper is first to provide extensive calculations that we hope will stimulate others to reexamine the issue."

Further research into the multiple-impact hypothesis is already underway. One of Rufu's collaborators, physicist Hagai Perets of the Technion ― Israel Institute of Technology, is already working to find out the efficiency of moonlet mergers. Rufu and her adviser also plan to study the moonlet-merging process "to understand the mixing of the moonlets inside the final moon."

This graphic illustrates how the moon may have formed after multiple collisions on Earth. Moon- to Mars-sized impactors strike the Earth and leave a disk of debris orbiting the planet. The debris forms "moonlets" and migrate farther away from the Earth due to a tidal interaction, but eventually settle at a distance known as the Hill radius. Here, the moonlets merge to eventually form the moon.

Credit: Raluca Rufu, et al. / Nature Geoscience

 

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Venus has More Volcanoes than Other Planet

  There are more volcanoes on Venus than any other planet within our solar system

Volcanoes on Venus

Overview

 

Venus has more volcanoes than any other planet in the solar system. Over 1600 major volcanoes or volcanic features are known (see map), and there are many, many more smaller volcanoes. (No one has yet counted them all, but the total number may be over 100,000 or even over 1,000,000). These volcanoes come in a variety of forms. Most are either Large Shields or Smaller Shield volcanoes, but there are also many Complex Features, several Unusual Constructs, and a few Large Flow Features. None is known to be active at present, but our data is very limited. Thus, while most of these volcanoes are probably long dead, a few may still be active. 

Background

Venus is like the Earth in many ways. It is nearly the same size and it has a similar bulk composition. Of all the planets, its orbit around the sun is the closest to EarthUs orbit. It has both clouds and a thick atmosphere. Like the Earth, it even has a fairly young surface age (~500 million years). Despite these basic similarities, however, Venus differs greatly from the Earth in detail.

First, since the atmosphere is mostly CO2, Venus has an extreme Greenhouse Effect. In fact, the surface temperature on Venus is about 470!C (about 880!F). Further, the surface air pressure on Venus is about 90 times greater than that at sealevel on Earth. This is roughly equivalent to the WATER pressure on Earth one kilometer beneath the oceanUs surface. These surface conditions have two effects. (1) There is no water on the surface of Venus. Indeed, there is almost no water in the air, either. The clouds are mostly made of sulfuric acid and they are much, much higher than most clouds on the Earth. (2) Due to the high atmospheric pressure, the winds on Venus are also relatively slow. Thus, neither wind nor rain can really affect the surface on Venus. As a result, volcanic features will look freshly formed for a long time.

Second, Venus shows no evidence for plate tectonics. There are no long, linear volcano chains. There are no clear subduction zones. Although rifts are common, none look like the mid-ocean ridges on Earth. Also, continent-like regions are rare, and show none of the jigsaw fits seen on Earth. Thus, where volcanism on Earth mostly marks plate boundaries and plate movements, volcanism on Venus is much more regional and much less organized.

Third, volcanism on Venus shows fewer eruptive styles than on the Earth. Almost all volcanism on Venus seems to involve fluid lava flows. There is no sign of explosive, ash-forming eruptions on Venus, and little evidence for the eruption of sludgy, viscous lavas. This may reflect a combination of several effects. First, due to the high air pressure, venusian lavas need much higher gas contents than Earth lavas to erupt explosively. Second, the main gas driving lava explosions on Earth is water, which is in very short supply on Venus. Lastly, many viscous lavas and explosive eruptions on Earth occur near plate subduction zones. Thus, the lack of subduction zones should also reduce the likelihood of such eruptions on Venus. 

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Biggest Sun Scuti

                           UY Scuti

  UY Scuti is a red pulsating very luminous supergiant star that can be located in the constellation of Scutum.

UY Scuti is one of the largest giant stars in the milky way if not possibly the universe. It is not as some might think in our Solar System, it is the centre of its own Solar System. In fact, UY Scuti is located close to the supermassive Black Hole Sagittarius A*, the centre of our galaxy a.k.a. Galactic Centre. However as we are unable to measure all the stars, we will not know if that is the case that it is the largest in Universe. To put it in context, if the centre of UY Scuti was where our Sun was, the star`s radius would extend out to Jupiter or even as far as Saturn. The only other star that can challenge the star for size is NML Cygni. UY Scuti is marginally in the grand sphere of things bigger than NML Cygni and both if placed in our solar system, would stretch out further than the orbit of Jupiter. To put it another way, it is 1.708 times the Sun`s radius with a variance of about +/i 192.ref:Aanda. 

It is a semiregular variable star in that it expands and contracts on an irregular base. The star roughly pulsates about every 740 days. The figure given for its radius is the mean size. ref:wiki Due to its size, it is not going to live as long as Alpha Centauri which the later is a smaller but burns through its energy at a slower pace. It is currently fusing main helium, of whats left of its hydrogen reserves are small contained in its core. It will one day go supernova or more appropriately to say hypernova.

If you`re struggling to put UY Scuti`s size into context, try this. If the Earth was 20cm, the Sun would be 22 meters across and UY Scuti would be 40 km. To give you another idea of how big it is, it would take a plane travelling at the speed of light, 14.5 seconds to travel round the Sun, it would take seven hours for the same object to travel round UY Scuti.

You might think that because the star is a massive star, its temperature would match its size. The actual truth is far from that, UY Scuti`s temperature is about 3,000 kelvin based on the Hertzsprung-Russell diagram. Size does not normally equate to temperature, its the colour that dictates the temperature. The more blue, the less red it is, the hotter the temperature is. 

The location is an estimated location for the star but it gives you an idea where in the constellation`s boundary that the star can be located. Even though the star is very large, it is faint in the night sky and you will not be able to see it unaided without the help of a pair of binoculars or telescope. It was only discovered in 1860 by German astronomers at Bonn University during a night survey. Although, there is a star within the circle, I`m not saying it is UY SCUTI.

It will go supernova one day but even though it is a large star, it will not go supernova for nearly the next million years as it works through the elements in it core until it gets to Iron. After Iron, it will not be able to continue to fuse elements any further. It is expected to heat up and become a yellow hypergiant star and also most likely shrink as it is become a hypergiant. When it goes Supernova, we`ll be too far away for it to have any direct effect on our planet and whatever life is on the planet will be unaffected. Long before UY Scuti goes supernova, Betelgeuse will have gone supernova before hand and its a smaller star.It will either become a Neutron Star or a black hole. It is not a Black Hole now, just a very very large star nearing the end of its life.

It might well be a titch to the largest star in the universe but there being so many stars not just in this galaxy but others means we don`t know and will never know. The largest star could be in the Andromeda Galaxy for example or even in IC1101, the currently recognised largest galaxy so far discovered in the galaxy, we just don`t know. 

There is at yet no Extrasolar Planet (Exoplanet) discovered in orbit round the planet although possible, is probably most unlikely. A planet would be tiny compared to the star and detecting a planet from a wobble would be an immense challenge.

Location of UY Scuti

The location of the star in the galaxy is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is from celestial equator. The Declination is how up or down compared to the celestial equator and is expressed in degrees. For UY Scuti, the location is 18h 27m 36.5334 and -12 d 27 ` 58.866 .

Physical Properties/View of UY Scuti

UY Scuti has a spectral type of M4Ia-Iab. This means the star is (M) red coloured (Ia) very luminous supergiant. UY Scuti lies at a distance of 9,500.00 light years away from our Sun and our planet Earth or to put it another way, 2,912.65 parsecs away from the Sun. 

UY Scuti has an apparent magnitude of 11.20 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number. The stars temperature has been calculated at between 2400 and 3700 based on the Class Type and lookup at Wikipedia-Stellar Classification

UY Scuti Radius has been calculated as being 1,708.00 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,188,426,400.00. km.

Variable Type of UY Scuti

The star is a pulsating Semiregular s, which are giants or supergiants of intermediate and late spectral variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted.

UY Scuti Facts

Traditional Name	UY Scuti
Celestial Type	Star
Apparent Magnitude	11.20
Right Ascension (R.A.)	18h 27m 36.5334
Declination (Dec.)	-12 d 27 ` 58.866
Distance from the Sun / Earth	9,500.00 Light Years
Spectral Type	M4Ia-Iab
Colour	(M) red
Star Type	(Ia) very luminous supergiant.
Variable Star Class	Pulsating
Variable Star Type	Semiregular s, which are giants or supergiants of intermediate and late spectral
Radius (x the Sun)	1,708.00
Calculated Temperature Range	2,400.00 - 3,700.00

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