Dark Skies Turned Gray: Working in the Clouds
We awoke just after two in the afternoon to the eye-itching grogginess that inevitably follows a long night of observing. The afternoon light just barely peeked through the few windows in our dormitory rooms, located more than 60 meters (about 120 feet) below the Blanco Telescope, where we do our nightly work for the Dark Energy Survey (DES).
As we headed to the lunch-flavored breakfast in the cafeteria we spotted a procession of dark clouds to the southeast. To our dismay, the prevailing winds appeared to be carrying them toward us, and toward the Blanco.
During ‘breakfast,’ comprised of tasty fresh vegetables and sausage, we discussed last night’s observations and logistics, as well as plans for the upcoming night, including speculation about the impact of the potentially turbulent weather.
Wet and tumultuous skies scatter the light from distant galaxies and stars that were otherwise on straight paths toward the telescope. This can cause a blurring of images. For telescopes situated on Earth, the higher the mountain-top site, the better the chances of avoiding atmospheric disruptions. The Cerro Tololo Inter-American Observatory resides at about 2200 meters (or 7200 feet) and it enjoys clear, dry skies the vast majority of the time.
Occasionally, mother nature reminds us of her unpredictability and how precious each photon is. With only eight hours of night out of every 24, we need all the darkness we can get. On this afternoon in the early Chilean spring season, our hopes would succumb to the fickle weather. After lunch, we left the cafeteria and looked up to find that a low-flying cloud had come to rest on the mountain peak, enveloping the Blanco. This night, there would be no sky observations, and no photons would break through this wet, gray blanket.
The picture above is taken looking outward from the main door to the control room of the Blanco. The telescope operator, Claudio Aguilera from La Serena, Chile, arrives for the night’s (uneventful) work.
Written by: Det. B. Nord [FNAL]
Image Credit: Det. B. Nord
Welcome to the Darkness
On a dark mountain-top, a car’s brake lights redden the dome of a telescope. Behind it, stars appear to drift by as the Earth slowly turns. The telescope inside that dome, however, is looking farther and deeper into the universe than those nearby bright stars. Commanded by a veritable army of astronomers, our new camera is looking for evidence of the strangest stuff in the universe, dark energy. Our mission is called the Dark Energy Survey.
What is the Dark Energy Survey? It’s a cooperative effort between about 200 scientists at more than 25 institutions around the world. Together, we’ve designed and built the Dark Energy Camera, the most powerful unclassified digital imaging device in the world, and we’ve mounted it on the 4-meter Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile.
Over the next five years, we’re going to use this camera to measure hundreds of millions of galaxies and thousands of supernovae in an effort to understand dark energy. That’s the name given to the mysterious substance that is causing our universe to expand faster and faster. We’re going to map a portion of the southern sky in unprecedented detail in order to study this accelerating expansion.
And along the way, we’re going to take some beautiful pictures, and we’re going to share them with you here every week.
We’ll start with this composite photo of the dome that houses the Blanco telescope. This image was made by taking multiple 30-second exposures over several hours, then combining all the images of the sky with a single image of the dome. The red glow was caused by brake lights on the road in front of the dome. The center of the arcs of light in the sky is the South Pole – it’s fixed in space, and the Earth rotates around it.
We can also see some multi-colored dashed arcs of light, moving in different directions. Those were caused by airplanes.
Dark Energy Detectives 