NASA has produced a breathtaking 12-year time lapse movie of
the entire sky, demonstrating how the world around us has changed.
A NASA satellite observatory has developed a time-lapse film
that shows how the sky has changed over the course of a decade. We can see
cosmic wonders in photographs, but we can feel them in motion images. NASA's
NEOWISE space telescope is creating fascinating videos of the sky's movement
and change. NASA's Near-Earth Object Wide Field Infrared Survey Explorer, or
NEOWISE, captures photographs in all directions as it orbits the Sun every six
months. When the photos are stitched together, hundreds of millions of things
appear on this map. In essence, scientists made a time-lapse movie utilizing 18
all-sky maps (the 19th and 20th will be revealed in March 2023), demonstrating
developments over the last ten years.
Each map has a wealth of information about the universe for
astronomers. However, when viewed as a time-lapse, they become even more
helpful resources for helping students understand it. The maps can be compared
using time-domain astronomy to detect distant objects that have changed
brightness or position over time.
"The night sky appears to alter relatively
minimally," said Amy Mainzer, principle investigator of NEOWISE at the
University of Arizona. "Stars are constantly erupting and flashing
throughout the sky." Asteroids fly by. Black holes are tearing up stars.
"The universe is a tremendously lively and busy place."
From WISE to NEOWISE
WISE was launched in 2009 as an observatory charged with
scouring our galaxy for and studying things outside our solar system. NEOWISE
began as a data processing project to retrieve WISE asteroid detections.
Cryogenically cooled detectors on the spaceship detected infrared light. Some
of the world's brightest galaxies and cool, nearby stars emit infrared light,
which the human eye cannot see. The WISE mission ended in 2011 when the coolant
on board ran out, but the spacecraft and part of its infrared detectors
remained operational. As a result, NASA reconfigured the device in 2013 to
track asteroids and other near-Earth objects. Both the mission and the
spacecraft were renamed NEOWISE. Despite the shift, astronomers continue to
investigate objects outside our solar system using data from infrared
telescopes.
As part of the CatWISE project, a catalogue of objects from
12 NEOWISE all-sky maps was provided in 2020. Brown dwarfs, which are
distributed around the galaxy and lurk in the dark near to our Sun, are studied
in this collection. Even though they originate like stars, brown dwarfs do not
undergo the fusion process that causes stars to light. Brown dwarfs appear to
travel quicker than more distant stars moving at the same speed because of
their proximity to Earth. Brown dwarfs can be found in the catalogue by looking
for things that move among billions of others. Backyard Worlds: Planet 9 is a
companion project to CatWISE that invites citizen scientists to pore through
NEOWISE data.
Brown Dwarf Mapping
Using WISE's original two all-sky scans, some 200 brown
dwarfs were discovered within 65 light-years of our Sun. As a result of the new
maps, 60 more Y-dwarfs, the coldest brown dwarfs, have been detected. Warmer
brown dwarfs could provide a different story about how and when they formed
than Y-dwarfs. As a result of these discoveries, our solar neighbourhood is now
ornamented with a variety of objects. A more complete census of brown dwarfs
close to the Sun allows scientists to calculate how efficient star creation is
in our galaxy.
A decade of studying the sky has also helped scientists
comprehend how stars emerge. Dusty blankets shroud protostars as they evolve
into stars, allowing NEOWISE to look inside their obscuring cocoons. Over time,
the dust clouds that surround protostars gather mass, causing them to flicker
and flare. To gain a better understanding of how stars originate, astronomers
utilize NEOWISE to track the lifecycles of almost 1,000 protostars through
time.
NEOWISE data has also contributed to a better understanding
of black holes. As part of the original WISE study, millions of supermassive
black holes were identified at the centres of distant galaxies. Recently,
NEOWISE data and an echo mapping approach were utilized to determine the size
of hot gas discs surrounding faraway black holes. A telescope cannot see these
objects because they are too small. Overall, NEOWISE has made significant
contributions to our understanding of the solar system, neighbouring stars, as
well as distant, hidden objects like supermassive black holes.
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