Neptune’s blue-green atmosphere is shown in greater detail than ever before by the Voyager 2 spacecraft as it rapidly approaches its encounter with the giant planet.
This color image, produced from a distance of about 16 million kilometers, shows several complex and puzzling atmospheric features.
The Great Dark Spot (GDS) seen at the center is about 13,000 km by 6,600 km in size – as large along its longer dimension as the Earth.
The bright, wispy “cirrus-type” clouds seen hovering in the vicinity of the GDS are higher in altitude than the dark material of unknown origin which defines its boundaries.
A thin veil often fills part of the GDS interior, as seen on the image.
The bright cloud at the southern (lower) edge of the GDS measures about 1,000 km in its north-south extent.
The small, bright cloud below the GDS, dubbed the “scooter,” rotates faster than the GDS, gaining about 30 degrees eastward (toward the right) in longitude every rotation.
Bright streaks of cloud at the latitude of the GDS, the small clouds overlying it, and a dimly visible dark protrusion at its western end are examples of dynamic weather patterns on Neptune, which can change significantly on time scales of one rotation (about 18 hours).
Galileo Zooms in on Jupiter’s Red Spot
This storm system is Jupiter’s Great Red Spot and it was captured in detail by Galileo. Using real images from three color filters, the Galileo team was able to compute what a person would see if able to float just above this ancient rotating cloud system.
So I recently moved to Tornado Alley yeah? Well, apparently there was a huge storm complete with tornado on Friday. Did I notice anything? No, I sat under my window the entire night on the computer. Only looked out when my cousin texted me asking if I made it through the tornado unscathed. It did look a little green though I didn’t see rotating clouds and I certainly don’t have a doppler. Now both my grandparents have checked in with me about it and idk what to say, I learned tornado impassivity from Nancy Drew?
Ororo snaps out of her
reverie to find a small concentration of dark clouds gently rotating in
Asgard’s otherwise clear sky. She dissipates the burgeoning storm with a
brief moment of concentration and a flick of her finger. When she turns
to Thor she is composed, mask once more in place. One look at him and the
gentle, understanding look on his face, and she spins back to stare out
at the endless blue.
His hands settle on
her shoulders as he comes to stand behind her. He is quiet, a solid
presence at her back radiating warmth and compassion.
An international research team led by a Japanese astronomer has determined how the enigmatic gas flow from a massive baby star is launched. The team used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the baby star and obtained clear evidence of rotation in the outflow. The motion and the shape of the outflow indicate that the interplay of centrifugal and magnetic forces in a disk surrounding the star plays a crucial role in the star’s birth cry.
Stars form from gas and dust floating in interstellar space. But, astronomers do not yet fully understand how it is possible to form the massive stars seen in space. One key issue is gas rotation. The parent cloud rotates slowly in the initial stage and the rotation becomes faster as the cloud shrinks due to self-gravity. Stars formed in such a process should have very rapid rotation, but this is not the case. The stars observed in the universe rotate more slowly.
How is the rotational momentum dissipated? One possible scenario involves the gas emanating from baby stars. If the gas outflow rotates, it can carry rotational momentum away from the system. Astronomers have tried to detect the rotation of the outflow to test this scenario and understand its launching mechanism. In a few cases signatures of rotation have been found, but it has been difficult to resolve clearly, especially around massive baby stars.
The team of astronomers led by Tomoya Hirota, an assistant professor at the National Astronomical Observatory of Japan (NAOJ) and SOKENDAI (the Graduate University for Advanced Studies) observed a massive baby star called Orion KL Source I in the famous Orion Nebula, located 1,400 light-years away from the Earth. The Orion Nebula is the closest massive-star forming region to Earth. Thanks to its close vicinity and ALMA’s advanced capabilities, the team was able to reveal the nature of the outflow from Source I.
“We have clearly imaged the rotation of the outflow,” said Hirota, the lead author of the research paper published in the journal Nature Astronomy. “In addition, the result gives us important insight into the launching mechanism of the outflow.”
The new ALMA observations beautifully illustrate the rotation of the outflow. The outflow rotates in the same direction as the gas disk surrounding the star. This strongly supports the idea that the outflow plays an important role in dissipating the rotational energy.
Furthermore, ALMA clearly shows that the outflow is launched not from the vicinity of the baby star itself, but rather from the outer edge of the disk. This morphology agrees well with the “magnetocentrifugal disk wind model.” In this model, gas in the rotating disk moves outward due to the centrifugal force and then moves upward along the magnetic field lines to form outflows. Although previous observations with ALMA have found supporting evidence around a low-mass protostar, there was little compelling evidence around massive protostars because most of the massive-star forming regions are rather distant and difficult to investigate in detail.
“In addition to high sensitivity and fidelity, high resolution submillimeter-wave observation is essential to our study, which ALMA made possible for the first time. Submillimeter waves are a unique diagnostic tool for the dense innermost region of the outflow, and at that exact place we detected the rotation,” explained Hirota. “ALMA’s resolution will become even higher in the future. We would like to observe other objects to improve our understanding of the launching mechanism of outflows and the formation scenario of massive stars with the assistance of theoretical research.”
TOP IMAGE….Artist’s impression of Orion KL Source I. The massive protostar is surrounded by a disk of gas and dust. The outflow is launched from the surface of the outer disk. Credit: ALMA (ESO/NAOJ/NRAO)
CENTRE IMAGE….Orion KL Source I observed with ALMA. The massive protostar is located in the center and surrounded by a gas disk (red). A bipolar gas outflow is ejected from the protostar (blue). Credit: ALMA (ESO/NAOJ/NRAO), Hirota et al.
LOWER IMAGE….The rotation of the outflow from Orion KL Source I imaged with ALMA. The color shows the motion of the gas; red shows gas moving away from us, whereas blue shows gas moving toward us. The disk is shown in white. Credit: ALMA (ESO/NAOJ/NRAO), Hirota et al.
WHAT LIES BENEATH: VENUS’ SURFACE REVEALED THROUGH THE CLOUDS
** Synopsis: Using observations from ESA’s Venus Express satellite, scientists have shown for the first time how weather patterns seen in Venus’ thick cloud layers are directly linked to the topography of the surface below. Rather than acting as a barrier to our observations, Venus’ clouds may offer insight into what lies beneath. **
Venus is famously hot, due to an extreme greenhouse effect which heats its surface to temperatures as high as 450 degrees Celsius. The climate at the surface is oppressive; as well as being hot, the surface environment is dimly lit, due to a thick blanket of cloud which completely envelops the planet. Ground-level winds are slow, pushing their way across the planet at painstaking speeds of about 1 metre per second – no faster than a gentle stroll.
However, that is not what we see when we observe our sister planet from above. Instead, we spy a smooth, bright covering of cloud. This cloud forms a 20-km-thick layer that sits between 50 and 70 km above the surface and is thus far colder than below, with typical temperatures of about -70 degrees Celsius – similar to temperatures found at the cloud-tops of Earth. The upper cloud layer also hosts more extreme weather, with winds that blow hundreds of times faster than those on the surface (and faster than Venus itself rotates, a phenomenon dubbed ‘super-rotation’).
While these clouds have traditionally blocked our view of Venus’ surface, meaning we can only peer beneath using radar or infrared light, they may actually hold the key to exploring some of Venus’ secrets. Scientists suspected the weather patterns rippling across the cloud-tops to be influenced by the topography of the terrain below. They have found hints of this in the past, but did not have a complete picture of how this may work – until now.
Scientists using observations from ESA’s Venus Express satellite have now greatly improved our climate map of Venus by exploring three aspects of the planet’s cloudy weather: how quickly winds on Venus circulate, how much water is locked up within the clouds, and how bright these clouds are across the spectrum (specifically in ultraviolet light).
“Our results showed that all of these aspects – the winds, the water content, and the cloud composition – are somehow connected to the properties of Venus’ surface itself,” says Jean-Loup Bertaux of LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales) near Versailles, France, and lead author of the new Venus Express study. “We used observations from Venus Express spanning a period of six years, from 2006 to 2012, which allowed us to study the planet’s longer-term weather patterns.”
Although Venus is very dry by Earth standards, its atmosphere does contain some water in the form of vapour, particularly beneath its cloud layer. Bertaux and colleagues studied Venus’ cloud-tops in the infrared part of the spectrum, allowing them to pick up on the absorption of sunlight by water vapour and detect how much was present in each location at cloud-top level (70 km altitude).
They found one particular area of cloud, near Venus’ equator, to be hoarding more water vapour than its surroundings. This ‘damp’ region was located just above a 4,500-metre-altitude mountain range named Aphrodite Terra. This phenomenon appears to be caused by water-rich air from the lower atmosphere being forced upwards above the Aphrodite Terra mountains, leading researchers to nickname this feature the ‘fountain of Aphrodite.’
“This ‘fountain’ was locked up within a swirl of clouds that were flowing downstream, moving from east to west across Venus,” says co-author Wojciech Markiewicz of the Max-Planck Institute for solar system Research in Göttingen, Germany. “Our first question was, ‘Why?’ Why is all this water locked up in this one spot?”
In parallel, the scientists used Venus Express to observe the clouds in ultraviolet light, and to track their speeds. They found the clouds downstream of the ‘fountain’ to reflect less ultraviolet light than elsewhere, and the winds above the mountainous Aphrodite Terra region to be some 18 percent slower than in surrounding regions.
All three of these factors can be explained by one single mechanism caused by Venus’ thick atmosphere, propose Bertaux and colleagues.
“When winds push their way slowly across the mountainous slopes on the surface they generate something known as gravity waves,” adds Bertaux. “Despite the name, these have nothing to do with gravitational waves, which are ripples in space-time – instead, gravity waves are an atmospheric phenomenon we often see in mountainous parts of Earth’s surface. Crudely speaking, they form when air ripples over bumpy surfaces. The waves then propagate vertically upwards, growing larger and larger in amplitude until they break just below the cloud-top, like sea waves on a shoreline.”
As the waves break, they push back against the fast-moving high-altitude winds and slow them down, meaning that winds above Venus’ Aphrodite highlands are persistently slower than elsewhere.
However, these winds re-accelerate to their usual speeds downstream of Aphrodite Terra – and this motion acts as an air pump. The wind circulation creates an upwards motion in Venus’ atmosphere that carries water-rich air and ultraviolet-dark material up from below the cloud-tops, bringing it to the surface of the cloud layer and creating both the observed ‘fountain’ and an extended downwind plume of vapour.
“We’ve known for decades that Venus’ atmosphere contains a mysterious ultraviolet absorber, but we still don’t know its identity,” says Bertaux. “This finding helps us understand a bit more about it and its behaviour – for example, that it’s produced beneath the cloud-tops, and that ultraviolet-dark material is forced upwards through Venus’ cloud-tops by wind circulation.”
Scientists already suspected that there were ascending motions in Venus’ atmosphere all along the equator, caused by the higher levels of solar heating. This finding reveals that the amount of water and ultraviolet-dark material found in Venus’ clouds is also strongly enhanced at particular places around the planet’s equator. “This is caused by the mountains way down on Venus’ surface, which trigger rising waves and circulating winds that dredge up material from below,” says Markiewicz.
As well as helping us understand more about Venus, the finding that surface topography can significantly affect atmospheric circulation has consequences for our understanding of planetary super-rotation, and of climate in general.
“This certainly challenges our current general circulation models,” says Håkan Svedhem, ESA Project Scientist for Venus Express. “While our models do acknowledge a connection between topography and climate, they don’t usually produce persistent weather patterns connected to topographical surface features. This is the first time that this connection has been shown clearly on Venus – it’s a major result.”
Venus Express was in operation at Venus from 2006 until 2014, when its mission concluded and the spacecraft began its descent through Venus’ atmosphere.
The study by Bertaux and colleagues made use of several years of Venus Express observations gathered by the Venus Monitoring Camera (VMC) – to explore the wind speeds and ultraviolet brightness of the clouds – and by the SPICAV (Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus) spectrometer – to study the amount of water vapour contained within the clouds.
“This research wouldn’t have been possible without Venus Express’ reliable and long-term monitoring of the planet across multiple parts of the spectrum. The data used in this study were collected over many years,” adds Svedhem. “Crucially, knowing more about Venus’ circulation patterns may help us to constrain the identity of the planet’s mysterious ultraviolet absorber, so we can understand more about the planet’s atmosphere and climate as a whole.”
I have got an increasing number of requests to write about Black Holes in the past couple of weeks. So, to kick-start we will start talking about Space-time Fabric.
When we usually talk of Gravitation we are bound to think like Newton, where objects are assumed to exerting a force upon each other. Like imaginary arrows of force in space. But this picture, although good for high school crumbled, with the advent of Einstein’s theory of Relativity. ( We will explore the question of why in an upcoming post.)
What is the Space-Time Fabric?
Think of spacetime fabric as an actual cloth of fabric. When you place an object on the fabric, the cloth curves. This is exactly what happens in the solar system as well.
The sun with such a huge mass bends the space-time fabric. And the earth and all the planets are kept in orbit by following this curvature that has been made by the sun.
The earth - moon system can be thought of in the same manner.
A natural question to ask at this juncture would be:
Why don’t planets just swirl into the sun?
To put it bluntly, they stay in their orbits because there is no other force in the Solar System which can stop them.
The Solar System was formed from a rotating cloud of gas and dust which spun around a newly forming star, our Sun, at its center. The sun did pull objects towards itself. But the planets that we see today were resilient and stuck with their course. And time passed, the net force acting on them turned to zero and will continue to be zero.
Gravity and Light.
Light is affected by the Gravity. This was discussed in a previous post about Gravitational Lensing.
The gravitational field of a really massive object is super strong. And this causes light rays passing close to that object to be bent and refocused somewhere else.
This is a consequence of the fact that space- time curvature is bent by objects which have a huge mass. When light is passing through this dent the rays of light are directed in another direction. And this causes effects like gravitational lensing.
**This post was inspired by this video - Gravity Visualized. Hope you enjoyed reading this post. If you have any doubts or queries, feel free to ask. Have a Good Day :)
astronomy has developed a lot.scientists have studied almost all planets.they are trying to figure out the formation of the planets.by doing so the came to know that the formation of jupiter, “the king of all planets” was a little bit different. jupiter’s formation initially, likely to be a star but a very different manner than stars form.thus it was called a “failed star”.
formation of stars
Stars form directly from the collapse of dense clouds of interstellar gas and dust. Because of rotation, these clouds form flattened disks that surround the central, growing stars. After the star has nearly reached its final mass, by accreting gas from the disk, the leftover matter in the disk is free to form planets.
a different jupiter
Jupiter is generally believed to have formed in a two-step process. First, a vast swarm of ice and rock ‘planetesimals’ formed. These comet-sized bodies collided and accumulated into ever-larger planetary embryos. Once an embryo became about as massive as ten Earths, its self-gravity became strong enough to pull in gas directly from the disk. During this second step, the proto-Jupiter gained most of its present mass (a total of 318 times the mass of the Earth). Soon thereafter, the disk gas was removed by the intense early solar wind, before Saturn could grow to a similar size.
brown dwarfs may look like planets but they form like stars–that is, they collapse directly from a gas cloud, rather than building up in the disk around a star. Brown dwarfs lack sufficient mass to shine, so they might more fairly be described as “failed stars.“
jupiter is formed of same elements such as hydrogen,helium as of the sun,but it is not massive enough pressure and temperature to fuse hydrogens to form helium ,which is the power source of stars.
binary star system
if jupiter had become a star,our solar system would have become a binary star system.a binary star system is those systems having two stars.they both revolve around themselves in their own orbits.it is interesting to note that most of the solar systems in the universe are binary,triple or higher multiple star systems but our sun is rather unusual.it is the sun which grabbed most of the mass during the formation of solar system.this made jupiter a failed star while in other systems the masses are more equitably distributed thus its still mysterious, scientists are trying to fathom these mysterious details of the birth process.
What is the difference between a hurricane, a tornado, and a twister?
A Hurricane is a Complex Mid latitude cyclone that is very developed and powerful, and can produce tornadoes. When you see a Low, or “L” on the weather channel, imagine that same system but with tropical energy and extremely developed, and that’s basically a Hurricane.
A Twister is a Slang term for Tornado, which is a high speed rotating cloud, that is ONLY When it touches down the ground. I.e if there is a spinning cloud that is above ground, its a funnel cloud. When it touches down, its a Tornado.
Experience: A student in meteorology
Also, a large difference in scale: a large tornado may be a mile wide. A small hurricane would be at least 60 or 70 miles wide.
Tornado warnings are measured in minutes. Hurricane warnings are often measured in days.