Tag Archives: planet

North America To Scale On Various Planets In Our Solar System

We’ve all seen images comparing the size of Earth with that of other planets in the solar system. The problem, John Brady of Astronomy Central realized, is that these images assume a grasp of Earth’s scale. So Brady decided to do something different and compare astronomical objects with pieces of the planet his readers may be familiar with

Suddenly, with the huge continent of North America dwarfed by Jupiter’s storms, the universe seems an even larger place. In the other direction, Mars looks so much more human-scaled.

John Brady/Astronomy Central. How the U.S. and Canada would measure up to Mars.

Brady has also reversed the process, showing what the solar system’s largest mountain, Olympus Mons, would look like if it replaced the Grand Canyon as Arizona’s prime tourist attraction. At 26 kilometers (85,000 ft) high, it would truly be a wonder, since the Earth’s greater gravity restricts mountains to a third of that size or less.

John Brady/Astronomy Central. If located appropriately, Olympus Mons would cover the whole state of Arizona.

Not everything makes us feel small. If you live in Liverpool, UK, you might be tempted to go for a bike ride around the area that Brady shows would be encompassed by a neutron star, or make an equivalent image for your own home with the help of satellite photos.

John Brady/Astronomy CentralNeturon stars really are the size of a city.
Brady told the Huffington Post, “I got the ‘North America on Jupiter’ image to scale by looking at size comparisons on NASA images of Earth compared to Jupiter’s Great Red Spot. The Mars image with North America placed over it was done by knowing the diameter of the red planet, then finding the distance between two U.S. cities. I used New York and San Francisco.” 

Read more: http://www.iflscience.com/space/universe-north-american-scale

Why Some Giant Planets Don’t Appear To Have Water

The largest study ever conducted of the atmospheres of planets circling other stars has revealedhow different they can be and explained why some appear to contain so little water and it seems to be that clouds are to blame, or a lack thereof.

The findings help us understand the circumstances that influence giant planets’ evolution, and confirm our suspicion that water is common even on planets so hot it can only exist as a gas.

Now that the excitement of merely finding planets beyond the Solar System has faded, astronomers are keen to learn more about these worlds than just their mass and orbital distance. Sadly, in most cases there is nothing we can discover with our current technology.

When a planet passes between its parent star andEarth the stars light is filtered through the atmosphere of the planet. Most of the planets we know about are either not positioned suitably for this, or are too distant to allow us to collect useful data. However, in a few cases,enough light can be collected for astronomers to see which wavelengths of light have been absorbed in passing through the planetary atmosphere.

Each type of molecule has a unique signature of absorbed wavelengths, so the light that reaches us reveals the atmospheric content. In Naturea teamled by Dr. David Singof the University of Exeterhave conducted a study of ten planets’ atmospheres, the most ever done in such a way, allowing comparisons between them.

A further step forward was the use of both the Hubble and Spitzer Space Telescopes for a single study. Hubble collects visible and nearby wavelengths while Spitzer operates in the infrared. This is the first time we’ve had sufficient wavelength coverage to be able to compare multiple features from one planet to another,” said Sing in a statement.We found the planetary atmospheres to be much more diverse than we expected.”

All the planets involved are so-called hot Jupiters, gas giants that orbit very close to their parent stars.

Among the ten worlds studied were two planets that have made headlines before. HD 209458b, located 150 light-years away in the Pegasus constellation, was the first extrasolar planet found that transits its parent star, as seen from Earth, and the first proven to have an atmosphere. Just last monthHD 189733b,which is a relatively close 63 light-years away, was reported to have wind speeds of thousands of kilometers an hour.

Both these two,along with a third planet, Wasp-12b, were reported last year as being surprisingly dry,with between a tenth and a thousandth of their expected concentrations of atmospheric water. This was puzzling because some planets in this class are rich in water.

When comparing the ten planets, the researchers realized that those with plenty of detectable water also lacked clouds that would interfere with the light reaching Earth. On the other hand, the low-water planets were cloudy, leading the authors to conclude that theclouds are interfering with our capacity to identify the water in those atmospheres.

Read more: http://www.iflscience.com/space/why-some-giant-planets-dont-appear-have-water

Hubble Spies Blue Planet — It’s Not Earth

Blue-planet

As far as planets go, HD 189733b — a giant, sizzling Jupiter-like world that swoops around its parent star every 2.2 days — couldn’t be more different from Earth. But the planet, located 63 light-years away in the constellation Vulpecula (the Fox), has one feature that assimilates it with our home planet: its blue color.

Astronomers weren’t specifically thinking about HD 189733b’s color, per se, when they requested observation time on the Hubble Space Telescope. They were following up previous studies showing the planet had clouds with an attempt to learn more about its atmosphere.

As HD 189733b paraded around its star, astronomers used Hubble’s light-splitting spectrograph to home in on specific wavelengths of light reflecting off the planet’s surface.

HD 189733b is a so-called “transiting planet” meaning it passes in front of and then behind its host star, relative to the telescope’s line of sight. Taking data before, during and after eclipses often yields scientific treasures — and, in this case, an aesthetic one as well.

When HD 189733b slipped behind the star, the light seen by Hubble dropped deeply into the blue part of the electromagnetic spectrum while all other colors remained the same — a telltale sign of the planet’s color.

HD 189733b is far too hot for liquid water, but there are other molecules that could scatter blue light, mirroring what happens in Earth’s atmosphere. Scientists believe HD 189733b has clouds made of liquid glass.

“Our best guess is that the color is due to a combination of reflection by silicate clouds and absorption by sodium atoms,” University of Exeter Professor of Planetary Science Frederic Pont wrote in an email to Discovery News.

“Other factors may be photochemical aerosols — i.e. smog — and absorption by other atoms or molecules than sodium,” though presently are no specific candidates,” he added.

Driving the planet’s extreme environment is its unenviable position 30 times closer to its parent star than Earth orbits the sun. At that distance, surface temperatures reach more than 1,800 degrees Fahrenheit.

To boot, the planet is likely gravitationally locked with one side permanently facing its star and the other in darkness. That dichotomy can generate wild winds that surpass 4,350 mph.

“I think of this planet in some ways as being about as alien a planet as you could possibly imagine,” astronomer Heather Knutson, with the California Institute of Technology in Pasadena, told Discovery News.

“If we could actually see it in person, I think we would find that there’s no good comparison we could make with anything that we’re familiar with. That’s what makes it interesting,” she added.

The research will be published in the Aug. 1 issue of Astrophysical Journal Letters.

Image courtesy of NASA, ESA, M. Kornmesser

This article originally published at Discovery News
here

Read more: http://mashable.com/2013/07/11/hubble-blue-planet/

NASA’s New Horizons Readies for This Summer’s Pluto Flyby

After traveling nearly five billion kilometers over nine years, NASA’s New Horizons spacecraft has just entered the first phase of approach in its upcoming epic encounter with Pluto. The series of several planned approaches will culminate on July 14 with the first ever close-up flyby of Pluto—a dwarf planet 7.5 billion kilometers (4.67 billion miles) from Earth.  

New Horizons, launched into space on January 19, 2006, is the first mission to the former ninth planet. The spacecraft woke up from its final hibernation period just last month to English tenor Russell Watson’s “Where My Heart Will Take Me.” Since 2007, the piano-sized probe has spent 1,873 days (or two-thirds of its flight time) largely unpowered over the course of 18 separate hibernation periods to reduce wear and tear. 

“We’ve completed the longest journey any spacecraft has flown from Earth to reach its primary target, and we are ready to begin exploring,” New Horizons principal investigator Alan Stern from Southwest Research Institute says in a news release

The plan is to head into the orbit of one of Pluto’s five known moons. And in preparation for this summer’s close encounter, scientists have been configuring the probe for distant observations of Pluto, including a long-range photo shoot beginning January 25 and continuing through the next few months. Images taken by the on-board Long-Range Reconnaissance Imager will help navigate the probe across the last 220 million kilometers (135 million miles).

“We need to refine our knowledge of where Pluto will be when New Horizons flies past it,” says Mark Holdridge of Johns Hopkins University’s Applied Physics Laboratory. “The flyby timing also has to be exact, because the computer commands that will orient the spacecraft and point the science instruments are based on precisely knowing the time we pass Pluto—which these images will help us determine.” 

This first approach phase will run until the spring, and various instruments on New Horizons will be gathering interplanetary data continuously, including measurements of high-energy particles streaming from the sun and the concentrations of dust particles in the Kuiper Belt, an unexplored area in the outer region of our solar system that could contain thousands of small icy, rocky planets.

Then in the springtime, cameras and spectrometers aboard the spacecraft will begin capturing high-resolution images that’ll help map Pluto and its moons more accurately than ever before. “We really are on Pluto’s doorstep,” Stern says.

Read more: http://www.iflscience.com/space/nasas-new-horizons-readies-summers-pluto-flyby

Robot Spacecraft Snaps Uranus Through Rings of Saturn

Uranus_montage

This NASA image depicts Uranus and its five moons.
Image: NASA

The robotic NASA spacecraft Cassini has been touring the solar system for 17 years now — and it just caught its first glimpse of one of the most remote planets.

Cassini has been focused on Saturn, but turned its gaze away long enough to snap this photo of distant Uranus, taken while it was almost on the complete opposite side of the Sun from Uranus. NASA says it was 28.6 astronomical units away from the ice giant at the time — or roughly 2.6 billion miles.

Here’s Cassini’s first photo of Uranus, the tiny blue dot seen through some of Saturn’s rings.

Uranus Photo
The spec of blue light in the top left corner of the photo is the ice-giant planet Uranus.


Image: NASA

The spacecraft has been hovering around Saturn since 2004, and is outfitted with cameras and equipment to measure atmospheric conditions and light spectra. It delivered a probe called Huygens that descended onto the surface of Saturn’s largest moon Titan, known to have an atmosphere and liquid water.

Uranus and Neptune, the 7th and 8th planets from the Sun, are commonly referred to as “ice giant” planets. Both are mostly composed of frozen water, ammonia and methane.

Read more: http://mashable.com/2014/05/02/nasa-spacecraft-uranus/

Life Could Be Possible On Sideways Exoplanet If It Has Oceans

Until now, researchers believed a factor in the habitability potential of an exoplanet involved its obliquity, or its axial tilt relative to the parent star. They thought that if a planet tilted mostly on its side, it would be unable to support life—even if it resided in the habitable zone. However, a new model indicates that life could survive those conditions, provided it was covered in oceans. The study was led by David Ferreira, then at MIT, and the paper was published in Icarus.

Earth has a relatively low obliquity of 23.5?. As the planet spins about its axis, the entire surface of the planet experiences exposure to daylight as well as getting a break from the sun at night (with some seasonal exceptions for locations closer to the poles). This allows the overall surface temperature to even out, like cooking on a rotisserie. 

It was traditionally believed that if a planet had an obliquity closer to that of Uranus (98?) and a pole directly facing the parent star, one side would be in perpetual direct sunlight for half of the year, while the other side would be ice cold. These extreme overheating/freezing cycles would create inhospitable conditions for life. However, Ferreira’s group found that the presence of oceans could balance things out.

“The expectation was that such a planet would not be habitable: It would basically boil, and freeze, which would be really tough for life,” Ferreira said in a press release. “We found that the ocean stores heat during summer and gives it back in winter, so the climate is still pretty mild, even in the heart of the cold polar night. So in the search for habitable exoplanets, we’re saying, don’t discount high-obliquity ones as unsuitable for life.”

Ferreira’s team made models for three planets in a star’s habitable zone, differing only in axial tilt. The planets had respective obliquities of 23?, 54?, and 90?, and were subjected to simulations of variable ocean depths and atmospheric conditions. Even for the planet with the greatest obliquity, an ocean as shallow as 50 meters (164 feet) would be enough to create an average temperature of 15?C (60?F) over the course of the year.

“We were expecting that if you put an ocean on the planet, it might be a bit more habitable, but not to this point,” Ferreira continued. “It’s really surprising that the temperatures at the poles are still habitable.”

However, if the oceans were too shallow, the planet would not be able to keep itself warm. Simulations of water 10 meters (32 feet) deep resulted in a runaway snowball effect, where the ice would freeze over completely on the dark side. Later during the year when the ice was exposed to the star, it would reflect too much sunlight to be heated. Ice would begin to form during this time on the other side, resulting in a planet that is completely frozen over.

“Some people have thought that a planet with a very large obliquity could have ice just around the equator, and the poles would be warm,” Ferreira concluded. “But we find that there is no intermediate state. If there’s too little ocean, the planet may collapse into a snowball. Then it wouldn’t be habitable, obviously.”

This modeling is purely hypothetical, and does not represent any specific currently-identified exoplanet. Out of the 2,000 exoplanets currently identified, only about three or four have water-like densities and would possibly fit this bill. However, understanding that high obliquity is not an automatic deal breaker to a planet’s potential habitability is very important as the study of exoplanets continues to move forward.

Read more: http://www.iflscience.com/space/life-could-be-possible-sideways-exoplanet-if-it-has-oceans