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[Music throughout] 

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Almost all observations of the universe

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come by collecting
light in various wavelengths.

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This light can show variations
in brightness,

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reveal structure in cosmic objects,
and contain huge amounts of information

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in how its wavelengths are distributed
across a spectrum.

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Researchers have captured these details
for decades, even centuries.

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But often they are limited to just a brief
snapshot of an object in space.

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A single still image.

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 In recent years,

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scientists have been making
more observations with a fourth component: time.

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Space isn't static, and recording data
through a given duration called 

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Time-Domain Astronomy tracks
how details of an object like brightness,

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spectrum, location and structure
change. An object can vary,

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it can move, or it can do both.

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There are three main classes
of how an object can vary in time.

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Periodic, quasiperiodic, and transient. Periodic change

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means there is a regular fixed pattern
to the change.

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Sunrise and sunset
or a blinking pulsar are examples.

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Quasiperiodic means
that there is a pattern and the change

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or event happens again and again,
but not as regularly,

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like hurricanes or flashes
from hot material around black holes.

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Transient events are less predictable
and often happen only once.

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Earthquakes and supernovas are transients.

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These are the hardest to observe because
they can be brief and start unexpectedly.

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If telescopes aren't looking in the
right place, they miss the beginning or

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even the entire event.

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NASA's upcoming

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Nancy Grace Roman Space
Telescope will be specially equipped

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to be a groundbreaking tool for Time-Domain Astronomy.

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It will observe from space
so it won't have daily time restrictions

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like ground based telescopes,
which can only observe at night.

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It will have image quality like Hubble,
but with a field of view

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at least 100 times larger.

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So it will be able to observe
large portions of the sky all at once.

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Roman is a survey mission,
which means that in addition to a large,

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singular field of view,

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Roman can repoint that view
more efficiently during observation

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periods, tiling even larger areas of sky
1000 times faster than Hubble.

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For one of these, called the Galactic Bulge
Survey,

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Roman will aim its expansive view
at the center of our galaxy

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and observe a two-square-degree region
in infrared wavelengths

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that cut through the obscuring dust
to reveal millions of stars.

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During this survey, Roman will take a new image

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every 2 minutes for more than 62 days
and then repeat this six times over

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five years for a total of 400 days of coverage.

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Roman will be watching for planets
transiting, or eclipsing, their host stars

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and rare gravitational lensing events
where the gravity of foreground objects

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lenses the light of background stars
causing changes in brightness.

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These peaks can reveal new planetary
systems, rogue planets

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untethered to a star, and even black holes
that would otherwise be invisible.

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A single snapshot of the sky
can't show these events;

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they require constant
or very regular monitoring to reveal.

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Roman’s main objective in this survey is
simply finding new planets and black holes.

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Astronomers anticipate
that Roman could discover over 1,000

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microlensing and 100,000
transiting planets from this survey alone.

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Observatories like the James Webb Space Telescope

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can then follow up with a narrower,
more targeted view

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and learn key details
about the most interesting discoveries.

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Roman will also perform time-oriented surveys 
aimed at furthering our

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understanding of the universe's history
and future. With its wide and steady gaze,

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the Nancy Grace Roman Space Telescope will be
a key player in the future of Time-Domain Astronomy.

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[NASA]