18 Jan, 2018
2017 Was One of Our Planet’s Hottest Years on Record
We just finished the second hottest year on Earth since global temperature estimates first became feasible in 1880. Although 2016 still holds the record for the warmest year, 2017 came in a close second, with average temperatures 1.6 degrees Fahrenheit higher than the mean.
2017’s temperature record is especially noteworthy, because we didn’t have an El Niño this year. Often, the two go hand-in-hand.
El Niño is a climate phenomenon that causes warming of the tropical Pacific Ocean waters, which affect wind and weather patterns around the world, usually resulting in warmer temperatures globally. 2017 was the warmest year on record without an El Niño.
We collect the temperature data from 6,300 weather stations and ship- and buoy-based observations around the world, and then analyze it on a monthly and yearly basis. Researchers at the National Oceanic and Atmospheric Administration (NOAA) do a similar analysis; we’ve been working together on temperature analyses for more than 30 years. Their analysis of this year’s temperature data tracks closely with ours.
The 2017 temperature record is an average from around the globe, so different places on Earth experienced different amounts of warming. NOAA found that the United States, for instance, had its third hottest year on record, and many places still experienced cold winter weather.
Other parts of the world experienced abnormally high temperatures throughout the year. Earth’s Arctic regions are warming at roughly twice the rate of the rest of the planet, which brings consequences like melting polar ice and rising sea levels.
Increasing global temperatures are the result of human activity, specifically the release of greenhouse gases like carbon dioxide and methane. The gases trap heat inside the atmosphere, raising temperatures around the globe.
We combine data from our fleet of spacecraft with measurements taken on the ground and in the air to continue to understand how our climate is changing. We share this important data with partners and institutions across the U.S. and around the world to prepare and protect our home planet.
Earth’s long-term warming trend can be seen in this visualization of NASA’s global temperature record, which shows how the planet’s temperatures are changing over time, compared to a baseline average from 1951 to 1980.
Learn more about the 2017 Global Temperature Report HERE.
Discover the ways that we are constantly monitoring our home planet HERE.
Posted in NASA and tagged Space by cnkguy with no comments yet.
17 Jan, 2018
The Beauty of Webb Telescope’s Mirrors
The James Webb Space Telescope’s gold-plated, beryllium mirrors are beautiful feats of engineering. From the 18 hexagonal primary mirror segments, to the perfectly circular secondary mirror, and even the slightly trapezoidal tertiary mirror and the intricate fine-steering mirror, each reflector went through a rigorous refinement process before it was ready to mount on the telescope. This flawless formation process was critical for Webb, which will use the mirrors to peer far back in time to capture the light from the first stars and galaxies.
The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2019. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.
A polish and shine that would make your car jealous
All of the Webb telescope’s mirrors were polished to accuracies of approximately one millionth of an inch. The beryllium mirrors were polished at room temperature with slight imperfections, so as they change shape ever so slightly while cooling to their operating temperatures in space, they achieve their perfect shape for operations.
The Midas touch
Engineers used a process called vacuum vapor deposition to coat Webb’s mirrors with an ultra-thin layer of gold. Each mirror only required about 3 grams (about 0.11 ounces) of gold. It only took about a golf ball-sized amount of gold to paint the entire main mirror!
Before the deposition process began, engineers had to be absolutely sure the mirror surfaces were free from contaminants.
The engineers thoroughly wiped down each mirror, then checked it in low light conditions to ensure there was no residue on the surface.
Inside the vacuum deposition chamber, the tiny amount of gold is turned into a vapor and deposited to cover the entire surface of each mirror.
Primary, secondary, and tertiary mirrors, oh my!
Each of Webb’s primary mirror segments is hexagonally shaped. The entire 6.5-meter (21.3-foot) primary mirror is slightly curved (concave), so each approximately 1.3-meter (4.3-foot) piece has a slight curve to it.
Those curves repeat themselves among the segments, so there are only three different shapes — 6 of each type. In the image below, those different shapes are labeled as A, B, and C.
Webb’s perfectly circular secondary mirror captures light from the 18 primary mirror segments and relays those images to the telescope’s tertiary mirror.
The secondary mirror is convex, so the reflective surface bulges toward a light source. It looks much like a curved mirror that you see on the wall near the exit of a parking garage that lets motorists see around a corner.
Webb’s trapezoidal tertiary mirror captures light from the secondary mirror and relays it to the fine-steering mirror and science instruments. The tertiary mirror sits at the center of the telescope’s primary mirror. The tertiary mirror is the only fixed mirror in the system — all of the other mirrors align to it.
All of the mirrors working together will provide Webb with the most advanced infrared vision of any space observatory we’ve ever launched!
Who is the fairest of them all?
The beauty of Webb’s primary mirror was apparent as it rotated past a cleanroom observation window at our Goddard Space Flight Center in Greenbelt, Maryland. If you look closely in the reflection, you will see none other than James Webb Space Telescope senior project scientist and Nobel Laureate John Mather!
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Posted in NASA and tagged Space by cnkguy with no comments yet.
13 Jan, 2018
Milky Way panorama, seen from a highway in New Hampshire. js
Milky Way panorama, seen from a highway in New Hampshire.
Source: Just Space
Posted in Just Space and tagged Space by cnkguy with no comments yet.