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"The sun appears so small from that distance that you could completely block it out with the head of a pin," said Dr. Mike Brown, California Institute of Technology (Caltech), Pasadena, Calif., associate professor of planetary astronomy and leader of the research team.
Sedna is extremely far from the sun, in the coldest known region of our solar system, where temperatures never rise above minus 240 degrees Celsius (minus 400 degrees Fahrenheit). The planetoid is usually even colder, because it approaches the sun only briefly during its 10,500- year solar orbit.
Sedna will come closer to Earth in the years ahead, but even at closest approach, about 72 years from now, Sedna is very far away--farther than Pluto. Then it will begin its 10,500-year trip back to the far reaches of the solar system. "The last time Sedna was this close to the sun, Earth was just coming out of the last ice age.
Since blue is at the high-frequency end of the visible spectrum, we say the light from an approaching star is shifted toward blue, or blueshifted.
Likewise, if a star is zooming away from you, any light it emits gets stretched. You see these stretched-out light waves as having a lower frequency. Since red is at the low-frequency end of the visible spectrum, we say that light from a receding star is shifted toward red, or redshifted.
Light emitted from galaxies moving toward you would be squished, making the wavelength shorter and the light bluer. On earth, we perceive the light from galaxies moving away from us (as it appears almost all galaxies are) . . . . as being somewhat stretched, with longer wavelengths that make it look redder.
The amount of the shift depends on the speed of the star, relative to you. For a moving object to create an appreciable redshift or blueshift requires some pretty serious speeds. To get just a 1% change in the frequency of light, a star has to be moving 1,864 miles per second. For a blue lightbulb to look red, it would have to be flying away from you at 3/4 of the speed of light.
After the ice age, they found, global average temperatures rose until they reached a plateau between 7550 and 3550 bc. Then a long-term cooling trend set in, reaching its lowest temperature extreme between ad 1450 and 1850.
Since Pluto is so far away from the Sun (at a average distance of 3,670,050,000 miles), the Sun would look much dimmer and smaller that it does from here on Earth. From Pluto, the Sun would look like a very bright star and would light up Pluto during the day about as much as the full Moon lights up Earth at night.
Pluto's highly elliptical orbit can take it more than 49 times as far out from the sun as Earth. It actually gets closer to the sun than Neptune for 20 years out of Pluto's 248-Earth-years-long orbit, providing astronomers a rare chance to study this small, cold, distant world. So after 20 years as the 8th planet (in order going out from the sun), in 1999, Pluto crossed Neptune's orbit to become the farthest planet from the sun (until it was demoted to the status of dwarf planet).
Compared with most of solar system's planets and moons, the Pluto-Charon system is tipped on its side in relation to the sun. Also, Pluto's rotation is retrograde compared to the other worlds — it spins backwards, from east to west.
Pluto's orbit is highly eccentric, or far from circular, which means its distance from the sun can vary considerably and at times, Pluto’s orbit will take within the orbit of the planet Neptune. When Pluto is closer to the sun, its surface ices thaw and temporarily form a thin atmosphere, mostly of nitrogen, with some methane.
As Pluto moves away from the Sun, during its 248 year-long orbit, its atmosphere gradually freezes and falls to the ground. In periods when it is closer to the Sun — as it is now — the temperature of Pluto’s solid surface increases, causing the ice to sublimate into gas.
In what is largely a reversal of an August announcement, astronomers today said Pluto is undergoing global warming in its thin atmosphere even as it moves farther from the Sun on its long, odd-shaped orbit.
The first occultation, in July, yielded limited data because of terrestrial cloud cover above key telescopes. Marc Buie, an astronomer at Lowell Observatory, scrambled to observe the event from northern Chile using portable 14-inch (0.35-meter) telescope. Afterward, Buie said he was baffled by what seemed to be global cooling of Pluto's atmosphere punctuated by some surface warming.
Then on Aug. 20, Pluto passed in front of a different star. The latter event provided much better data captured by eight large telescopes and seems to clarify and mostly reverse the earlier findings. ...astronomers today said Pluto is undergoing global warming in its thin atmosphere even as it moves farther from the Sun...
After the ice age, they found, global average temperatures rose until they reached a plateau between 7550 and 3550 bc.
Then a long-term cooling trend set in, reaching its lowest temperature extreme between ad 1450 and 1850.
Since then, temperatures have been increasing at a dramatic clip: from the first decade of the twentieth century to now, global average temperatures rose from near their coldest point since the ice age to nearly their warmest, Marcott and his team report today in Science1.
With such a large distance from the Sun, Pluto is incredibly cold. But this temperature can vary enough to change the dwarf planet significantly. At its closest point, it warms up enough so that Pluto’s nitrogen atmosphere sublimates and forms a diffuse cloud around it. As Pluto gets further away from the Sun; however its this atmosphere freezes out, and falls to the surface of Pluto like snow.
The surface of Pluto, in comparison, can range from a low temperature of 33 Kelvin (-240 degrees Celsius or -400 degrees Fahrenheit) and 55 Kelvin (-218 degrees Celsius or -360 degrees Fahrenheit). The average surface temperature on Pluto is 44 Kelvin (-229 Celsius or -380 Fahrenheit).
Using ESO's Very Large Telescope, astronomers have gained valuable new insights about the atmosphere of the dwarf planet Pluto. The scientists found unexpectedly large amounts of methane in the atmosphere, and also discovered that the atmosphere is hotter than the surface by about 40 degrees, although it still only reaches a frigid minus 180 degrees Celsius. These properties of Pluto's atmosphere may be due to the presence of pure methane patches or of a methane-rich layer covering the dwarf planet's surface.
Currently the Earth is tilted at 23.44 degrees from its orbital plane, roughly halfway between its extreme values. The tilt is in the decreasing phase of its cycle, and will reach its minimum value around the year 11,800 CE ; the last maximum was reached in 8,700 BCE. This trend in forcing, by itself, tends to make winters warmer and summers colder (i.e. milder seasons), as well as cause an overall cooling trend.
Mercury is getting smaller. Over its roughly 4.5 billion years of existence, the dense little planet’s diameter could have shrunk by as much as 14 kilometers, a study published today in Nature Geoscience reports.
But Mercury isn’t shrinking because of water loss. It’s getting smaller because its enormous metallic core is cooling and contracting.
Some scientists say we could be headed for another "Little Ice Age," given how eerily calm the sun has been in recent years.
“I’ve never seen anything quite like this," Dr. Richard Harrison, head of space physics at Rutherford Appleton Laboratory in England, told the BBC. "If you want to go back to see when the sun was this inactive in terms of the minimum we’ve just had and the peak that we have now, you’ve got to go back about 100 years.”
The Earth's inner core is a ball of solid iron about 1,500 miles (2,400 kilometers) wide, about the same size as the moon. This ball is surrounded by an outer core made up mostly of liquid iron-nickel alloy, a highly viscous mantle layer and, topping it off, a solid crust that forms the surface of the planet.
As the Earth cools from the inside out, the molten outer core is slowly freezing. This is leading the solid inner core to grow at a rate of approximately 1 millimeter per year. However, scientists now find that the inner core might be melting at the same time.
This melting could actually be linked to activity at the Earth's surface, the researchers said, and added that the discovery could help explain how the core generates the planet's magnetic field.
(Seriously, I'm not sure where you're going with this thread?)