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Pierre Markuse
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Pierre Markuse

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The Thing with Colors in Astronomy

You've seen many stunning and spectacular images of objects in space, galaxies, star clusters, supernova remnants, different nebulae and many more. Often those images are very colorful but sometimes images of the same object look very different.

But I see your true colors shining through...

Have a look at these images of the famous "Pillars of Creation" in the Eagle Nebula (M16, NGC 6611). The image on the left was taken by the Hubble Space Telescope, the image on the right by the MPG/ESO 2.2-metre telescope. As you can see, the colors are quite different. But how is that possible?

How we get color

Both images are actually composite images made from three monochromatic images taken through filters for different wavelengths. Those monochromatic images were then assigned ('mapped') to one of the three color channels in a digital image (Red, Green and Blue) which combined result in a color image. 

The images taken by those two telescopes used filters for different wavelengths, so after being combined the resulting images of course do look different.

But how would the object look like to the naked eye?

In most cases deep space objects seem very faint because of their distance and since our eyes (unlike a camera) can't change the exposure time to gather more light, colors are usually not very saturated, if visible to the naked eye at all, some objects are even too faint to trigger the cones in the eyes (the photoreceptor cells responsible for color vision) leaving us with a monochromatic view generated by the rods which are far more sensitive and triggered by less light.

But if we would have super-sensitive color vision, the "Pillars of Creation" would look more like the right image to our naked eyes. And here is why:

The Hubble Space Telescope image used filters with wavelengths of 673 nm, 657 nm and 502 nm and mapped those to the red, green and blue channel. And while 673 nm is indeed a reddish color mapped to the red channel, they mapped 657 nm, another red, to the green channel and 502 nm, a greenish color to the blue channel. The resulting color image is stunning and beautiful but not like what you would see with your naked eyes.

The MPG/ESO 2.2-metre telescope image used filters with wavelengths of 651 nm, 539 nm and 451 nm and mapped those to the red, green and blue channel. As you can see those three wavelengths are within the color range of the channel they are mapped to and therefore - when combined - result in an image close to what you could see with your naked eyes. That is, if you had super-vision, sensitive enough to see colors at all.

Aren't most colors fake then?

Some people would say the colors in the Hubble image are fake, because the image doesn't reflect what it would look like to the human eye. And while it's true that it does look different, the colors aren't fake. They are not chosen by some artist to make an impressive image, no, they reflect certain chemicals within the object and therefore are based on actual data. It is just a different way to look at the object to gather more information and the mapping of different filters to the red, green and blue channel helps visualizing the distribution of certain chemicals in the nebula. So those colors are not fake, they just focus on a different part of the spectrum. An image of you in the infrared part of the spectrum is still you and "real", although it does look a lot different than a "normal" photograph which uses the visible part of the spectrum.

In the image below you see both versions of the "Pillars of Creation" and the monochromatic images used for each channel. The color of the text more or less represents the color of the light mapped to the channel.

Take a look here to learn more about colors in astrophotography:
http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/

An image of the galaxy NGC 1512 demonstrating how different the same object can look in different wavelengths:
http://www.spacetelescope.org/images/heic0106a/

More on the Pillars of Creation:
https://en.wikipedia.org/wiki/Pillars_of_Creation

The fullsize Hubble image can be found here:
http://hubblesite.org/newscenter/archive/releases/2015/01/image/c/

The fullsize MPG/ESO 2.2-metre telescope image can be found here:
http://www.eso.org/public/images/eso0926a/

Image credit: Upper left: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) http://bit.ly/1Hr65ZD / Upper right: ESO http://bit.ly/1Hr5V4g CC BY 4.0 http://bit.ly/1K51Pjo / Edited by +Pierre Markuse 

#science   #astronomy   #color   #m16   #eaglenebula   #ngc6611   #pillarsofcreation   #astrophotography   #hubble   #space  
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This was very educational thank you. 
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Glaciers melt faster than ever

Glacier decline in the first decade of the 21st century has reached a historical record, since the onset of direct observations. Glacier melt is a global phenomenon and will continue even without further climate change. This is shown in the latest study by the World Glacier Monitoring Service under the lead of the University of Zurich, Switzerland.

Full story here:
http://www.mediadesk.uzh.ch/articles/2015/gletscher-verlieren-mehr-eis-als-je-zuvor_en.html

The world glacier monitoring service:
http://wgms.ch/

Where to start when looking for information on climate change?

Check out NASA's Global Climate Change Vital Signs of the Planet website with lots of information on global climate change:
http://climate.nasa.gov/

Image credit: Retreat of the Eyjabakkajökull outlet glacier of the Vatnajökull ice cap in Iceland comparing the situation in 2000 (image date) with 1991 and 1973 NASA GSFC Landsat/LDCM EPO Team http://1.usa.gov/1KMvzUF Landsat 7 ETM+ natural-color composite (bands 3, 2, 1) with outlines derived by D.K. Hall, R.S. Williams, Jr. and O. Sigurðsson, from Landsat 1 MSS and Landsat 5 TM data. Image processing by Marit Jentoft-Nilsen of NASA's Visualization Analysis Lab.

#science   #glacier   #glacierretreat   #climatechange   #earth   #wgms  
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I've seen evidence of glaciers melting at a rapid pace in Glacier National Park over a span of 30 years. The difference is striking.
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RCW 86 - Supernova remnant from 185AD Supernova

In this image we can see the supernova remnant RCW 86, the remnant of a 185 AD supernova (SN 185) witnessed by Chinese astronomers. It is located between the constellations Circinus and Centaurus about 8,000 light-years away from Earth.

The image combines X-ray data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton in blue and green as well as infrared data from NASA's Spitzer Space Telescope and NASA's Wide-Field Infrared Survey Explorer (WISE) here shown in yellow and red. The data shows that SN 185 was a type Ia supernova, a type of supernova used as standard candle to measure distances.

More information here:
http://chandra.harvard.edu/photo/2011/rcw86/
https://en.wikipedia.org/wiki/SN_185

Cosmic Distance Ladder

Type Ia supernovae are an important part of establishing distances in the Universe as they serve as a standard candle. They have a consistent absolute magnitude so from looking at the apparent magnitude you can calculate the distance.
http://en.wikipedia.org/wiki/Cosmic_distance_ladder#Standard_candles
https://en.wikipedia.org/wiki/Type_Ia_supernova

Image credit: X-ray: NASA/CXC/SAO & ESA; Infared: NASA/JPL-Caltech/B. Williams (NCSU) http://bit.ly/1JFHmpg

#science   #astronomy   #supernova   #rcw86   #sn185   #supernovaremnant   #chandra   #space   #type1asupernova  
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How beautiful and what magic and is it Ok to just appreciate this  and us being apart of it without an argument  or  a war about whose God or Savior created it ? ...Just once ?
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Pierre Markuse

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Star Cluster NGC 1929 in the N44 Nebula

In this image you can see the star cluster NGC 1929 in the N44 emission nebula located in the Large Magellanic Cloud (LMC) a satellite galaxy of the Milky Way in the constellation Dorado about 160,000 light-years away from Earth. The image is a composite image with X-ray data gathered by NASA's Chandra X-ray Observatory (blue), infrared data from NASA's Spitzer Space Telescope (red) and optical light from the 2.2m Max-Planck-ESO telescope (yellow). Stellar winds from the massive stars and shocks from the supernovae carve out superbubbles in the gas seen in X-rays by Chandra (blue). Infrared data shows dust (red) and cooler gas, and optical light (yellow) reveals where ultraviolet radiation from stars is ionizing the surrounding gas, causing it to glow as an emission nebula.

More information here:
http://chandra.harvard.edu/photo/2012/n1929/

More on the N44 nebula:
https://en.wikipedia.org/wiki/N44_(emission_nebula)

Another image of LHA 120-N44 taken by ESO’s Very Large Telescope showing the structure of the superbubble more clearly:
http://www.eso.org/public/images/eso1125a/

More on superbubbles:
https://en.wikipedia.org/wiki/Superbubble

What is an emission nebula?

An emission nebula is a cloud of ionized gas emitting light of various colors. More here:
https://en.wikipedia.org/wiki/Emission_nebula
https://en.wikipedia.org/wiki/H_II_region

Large Magellanic Cloud

The Large Magellanic Cloud (LMC) is a satellite galaxy of our Milky Way, its distance to Earth is about 160,000 light-years. It has a diameter of about 14,000 light-years and is it roughly 1/100 as massive as the Milky Way. More information here:
https://en.wikipedia.org/wiki/Large_Magellanic_Cloud

Image credit: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m http://bit.ly/1JDFhtR

#science   #astronomy   #ngc1929   #n44   #lmc   #emissionnebula   #space   #largemagellaniccloud   #superbubbles  
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Unbelievable
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Earth Flyby of 'Space Peanut' Captured in New Video

The video shows the rotation of the asteroid, named 1999 JD6 (diameter of about 200-300 meters), which made its closest approach on July 24 at 9:55 p.m. PDT (12:55 a.m. EDT on July 25) at a distance of about 7.2 million kilometers (4.5 million miles, or about 19 times the distance from Earth to the moon). The images for this video were acquired using bistatic observation, researchers paired NASA's 70-meter-wide (230-foot) Deep Space Network antenna at Goldstone, California, with the 100-meter (330-foot) National Science Foundation Green Bank Telescope in West Virginia. Using this approach, the Goldstone antenna beams a radar signal at an asteroid and Green Bank receives the reflections

Full story here:
http://www.jpl.nasa.gov/news/news.php?feature=4675

More information on near Earth Objects (NEOs) here:
http://neo.jpl.nasa.gov/

The Deep Space Network:
http://deepspace.jpl.nasa.gov/

Image credit: Near-Earth asteroid 1999 JD6 NASA/JPL-Caltech/NRAO http://1.usa.gov/1JVVoii

#science   #asteroid   #1999jd6   #radar   #bistaticobservation   #nearearthasteroid   #space   #dsn   #nasa  
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Space ship with gravity. 
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Binary Star System Precisely Timed with Pulsar's Gamma-rays

Scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) in Hannover, Germany, now have precisely measured the properties of a binary star system with a gamma-ray millisecond pulsar. Using new methods, the researchers analyzed archival data from the Fermi Gamma-ray Space Telescope more precisely than possible before. They discovered variations in the orbital period of the interacting binary system that can be explained by magnetic activity cycles of the companion star.

Full story here:
http://www.aei.mpg.de/1689465/GammaPSRTiming

What is a pulsar (pulsating radio star)?

A pulsar is a type of neutron star, those are extremely dense and massive stars made up almost entirely of neutrons.They are the result of a gravitational collapse of a massive star following a supernova. Pulsars are highly magnetized and have short rotational periods. They are emitting beams of electromagnetic radiation which, when oriented in a way so a beam is facing Earth, can be detected. Because pulsars are rotating this beam rotates in an out of view resulting in a pulsating signal. More information here:
https://en.wikipedia.org/wiki/Pulsar
https://en.wikipedia.org/wiki/Neutron_star
https://en.wikipedia.org/wiki/Supernova#Core_collapse

#science   #astronomy   #astrophysics   #pulsar   #binarystar   #binarystarsystem   #space   #fermi   #gammarays  
Pulsars are rapidly rotating compact remnants born in the explosions of massive stars. They can be observed through their lighthouse-like beams of radio waves and gamma-rays. Scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) in Hannover, Germany, ...
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Pierre Markuse

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Earth from Space: Tokyo Bay and Surroundings at Night

In this image taken from aboard the International Space Station (ISS) using a Nikon D3s digital camera and a focal length of 180mm you can see Tokyo Bay and the surrounding cities at night. The bright rectangle almost center image at the northern coast of Tokyo Bay is Haneda Airport, Tokyo's International airport. To the south-west of it you can see the Yokohama Maritime Port, to the north the bright lights of Tokyo.

The image was taken January 9th, 2011 at 10:04 GMT, the ISS was at an altitude of 343 kilometers (213 miles).

The area in Google maps:
https://goo.gl/EXPP1o

More images of Earth from Space?

If you are interested in space images you should take a look at the 
Gateway to Astronaut Photography of Earth website. It allows you to search and browse images taken from the ISS and other missions and you cannot only download JPG images but also the digital raw files if you are interested in editing them yourself. You can find the website here:
http://eol.jsc.nasa.gov/

Image credit: Astronaut photograph ISS026-E-16517 Earth Science and Remote Sensing Unit, NASA Johnson Space Center http://1.usa.gov/1HmMXKO / Edited by +Pierre Markuse 

#science   #internationalspacestation   #iss   #tokyo   #東京   #photography   #earth   #space  
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Terra Sirenum with Atlantis Chaos on Mars

In this image taken by the High Resolution Stereo Camera aboard the Mars Express Orbiter, an ESA spacecraft launched in 2003, you can see Terra Sirenum, located in the southern hemisphere of Mars. Red and white are elevated areas, blue/purple are low areas. At the center of the image you can see Atlantis Chaos, a lowland plain covering around 170 km by 145 km and containing a few hundred small peaks and flat-topped hills (flight-over in the video linked below). Some of the the craters and basins in this area may have held standing  water in the past.

More information here:
http://www.esa.int/spaceinimages/Images/2015/07/Ancient_Atlantis
https://en.wikipedia.org/wiki/Terra_Sirenum

Take a look at this flight over Atlantis video:
https://youtu.be/O_b39AHRMlw

More on the Mars Express orbiter and the High Resolution Stereo Camera:
http://sci.esa.int/mars-express/
https://en.wikipedia.org/wiki/Mars_Express
https://en.wikipedia.org/wiki/High_Resolution_Stereo_Camera

Image credit: Terra Sirenum ESA/DLR/FU Berlin http://bit.ly/1Ik0BjG CC BY-SA 3.0 IGA http://bit.ly/1CHtnbN

#science   #mars   #terrasirenum   #atlantischaos   #marssexpress   #space   #spaceexploration   #solarsystem   #esa  
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Pffft, derp, it's only a about a 500 km area shown... no wonder I can't find it xP
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Pierre Markuse

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Little Gem Nebula - NGC 6818

In this image taken by the Hubble Space Telescope we can see the planetary nebula NGC 6818, the Little Gem nebula, located in the constellation of Sagittarius (The Archer), about 6000 light-years away from Earth. Should you have images of other planetary nebulae in mind this one here seems to look different. The reason for that are the filters used in the different exposures of this combined image. This particular image is a combination of five different exposures using different filters with wavelengths of 658 nm, 656 nm, 502 nm, 487 nm and 427 nm all of which are in the visible part of the spectrum (which roughly covers wavelengths from  390 to 700 nm).

More information here:
https://www.spacetelescope.org/images/potw1531a/
https://en.wikipedia.org/wiki/NGC_6818

More on colors in astrophotography:
https://plus.google.com/+PierreMarkuse/posts/ALvpcmx2iHk

Another image of NGC 6818:
http://www.spacetelescope.org/images/opo9811h/

What is a planetary nebula?

A planetary nebula is basically a shell of glowing ionized gas ejected from old red giant stars. More here:
http://en.wikipedia.org/wiki/Planetary_nebula
http://en.wikipedia.org/wiki/Red_giant

Videos explaining planetary nebulae:
https://youtu.be/pQ4-m1vtTmE
https://youtu.be/4AT9ct-2-Rc

Image credit: NGC 6818 ESA/Hubble & NASA Acknowledgement: Judy Schmidt (geckzilla.comhttp://bit.ly/1IjTPdF CC BY 3.0 http://bit.ly/1BSTMl1

#science   #astronomy   #ngc6818   #planetarynebula   #hubble   #space   #littlegemnebula   #nebula  
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Fantastical!!
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The Open Cluster NGC 346

In this image taken by the Hubble Space Telescope you can see the open cluster NGC 346 located in the southern constellation Tucana (The Toucan) about 210,000 light-years away from Earth in the Small Magellanic Cloud. NGC 346 is a star-forming region with lots of infant stars and about 70,000 stars altogether. The image is a composite of two exposures one using a 555 nm filter (visible blue light, also shown in blue) and one a near-infrared filter of 814 nm (shown in red).

More on NGC 346:
https://en.wikipedia.org/wiki/NGC_346
http://www.esa.int/Our_Activities/Space_Science/Star-forming_region_in_nebula_NGC_346

The Small Magellanic Cloud

The Small Magellanic Cloud (SMC) is a dwarf irregular galaxy about 200,000 light-years away from Earth. More information here:
https://en.wikipedia.org/wiki/Small_Magellanic_Cloud

What is an open cluster?

An open cluster is a group of a few thousand stars that have their origin in the same stellar nursery and are roughly of the same age. More information here:
https://en.wikipedia.org/wiki/Open_cluster

More on star formation:
https://en.wikipedia.org/wiki/Star_formation

Image credit: NGC 346 http://bit.ly/1eHt2iW CC BY 3.0 http://bit.ly/1BSTMl1 

#science   #astronomy   #ngc346   #opencluster   #hubble   #space   #smc   #starformation  
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It's beautiful 
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Pierre Markuse

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Earth from Space: Algae Bloom in The Black Sea

In this image taken July 15, 2012 by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite you can see the Black Sea with a very distinct bloom of coccolithophores, a type of calcite-shedding phytoplankton, coloring big parts of the Black Sea cyan.

More on Coccolithophores:
http://earthobservatory.nasa.gov/Features/Coccolithophores/
https://en.wikipedia.org/wiki/Coccolithophore

Aqua (EOS PM-1) satellite

The Aqua satellite is part of the Earth Observing System (EOS, http://bit.ly/1DeuSni), its Moderate Resolution Imaging Spectroradiometer (MODIS) can take measurements in 36 spectral bands ranging in wavelength from 0.4 µm to 14.4 µm, another MODIS instrument is orbiting Earth aboard the Terra satellite

More on the Aqua satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) here:
http://aqua.nasa.gov/
https://en.wikipedia.org/wiki/Aqua_(satellite)
http://modis.gsfc.nasa.gov/about/design.php

Image credit: The Black Sea NASA/GSFC/MODIS http://bit.ly/1Detm4D / Edited by +Pierre Markuse 

#science   #earth   #aqua   #modis   #blacksea   #Coccolithophores   #spacetechnology   #algae   #terra  
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Super cool
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NASA's Spitzer Confirms Closest Rocky Exoplanet

Using NASA's Spitzer Space Telescope, astronomers have confirmed the discovery of the nearest rocky planet outside our solar system, larger than Earth and a potential gold mine of science data. Dubbed HD 219134b, this exoplanet, which orbits too close to its star to sustain life, is a mere 21 light-years away. HD 219134b is also the closest exoplanet to Earth to be detected transiting, or crossing in front of, its star and, therefore, perfect for extensive research.

More information here:
http://www.jpl.nasa.gov/news/news.php?feature=4672
http://www.spitzer.caltech.edu/images/6082-ssc2015-02b-Infrared-Light-Curve-for-Transiting-Exoplanet-HD-219134b

More on the Spitzer Space Telescope:
http://www.spitzer.caltech.edu/

How do we detect exoplanets?

If you have seven minutes and would like an easy and interesting explanation of different techniques (Doppler Technique, Direct Imaging, Light Curves, Transit Timing Variations, Microlensing) to detect planets in other star systems take a look at this video:
https://youtu.be/zFPnOUSdMdc

Image credit: This artist's conception shows the silhouette of a rocky planet, dubbed HD 219134b, as it passes in front of its star. NASA/JPL-Caltech http://1.usa.gov/1eE4Qhv

#science   #astronomy   #hd219134b   #spitzerspacetelescope   #exoplanet   #space   #transiting  
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That something else
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Never stop being curious...
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Hello!

Feel free to follow me or send me a message. (Also follow me on Twitter if you like.)

Some of you use circles to categorize people in different interest groups, and though I'm interested in lots of stuff you might wanna put me in circles like:
  • Science (General science and especially astronomy, physics and space technology)
  • Politics (also mostly stuff concerning science)
Mostly I do post science related stuff but be aware I'll write about anything that comes to mind. Just have a look at my posts and you'll see what exactly is going on.

If you expect an answer please stay nice and don't be a dick, it would also be a good idea to write English or German. French is also possible, but since my French is quite rusty I'll most probably answer English.
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