Astronomers Create a Digital Atlas of Over 380,000 Galaxies

In the observ­able uni­verse, there are esti­mat­ed to be between 200 bil­lion to two tril­lion galax­ies. By com­par­i­son to these super-Sagan­ian num­bers, the 383,620 galax­ies cap­tured by the Siena Galaxy Atlas may seem like small pota­toes. But the SGA actu­al­ly rep­re­sents a land­mark achieve­ment among dig­i­tal astron­o­my cat­a­logs: as Saman­tha Hill writes in Astron­o­my, it draws its data from three Dark Ener­gy Spec­tro­scop­ic Instru­ment Lega­cy Sur­veys, which togeth­er con­sti­tute “one of the largest sur­veys ever con­duct­ed.” Com­ing to 7,637 down­load­able pages, it “presents a new pos­si­ble nam­ing con­ven­tion for the galax­ies, and cap­tures images of the objects in opti­cal and infrared wave­lengths. Each of the target’s data set includes a whole slew of oth­er infor­ma­tion includ­ing its size and mor­phol­o­gy.”

Though pub­licly acces­si­ble online, the for­mi­da­bly tech­ni­cal SGA may present the non-astronomer with a some­what steep learn­ing curve. One way to approach the archive through some of the espe­cial­ly impres­sive galax­ies it cap­tures is to orga­nize the list below its search fil­ters accord­ing to size. The images that result are not, of course, pho­tographs of the kind any of us could take by point­ing a cam­era up at the night sky, no mat­ter how pricey the cam­era. Rather, they’re the results, processed into visu­al leg­i­bil­i­ty, of enor­mous amounts of data col­lect­ed by advanced tele­scope and satel­lite.

To get more tech­ni­cal, the SGA is also “the first cos­mic atlas to fea­ture the light pro­files of galax­ies  —  a curve that describes how the bright­ness of the galaxy changes from its bright­est point, usu­al­ly at the cen­ter, to its dimmest, com­mon­ly at its edge.”

So writes’s Robert Lea, who also explains more about the SGA’s use­ful­ness to sci­en­tif­ic pro­fes­sion­als. It “rep­re­sents peak accu­ra­cy, promis­ing to be a gold mine of galac­tic infor­ma­tion for sci­en­tists aim­ing to inves­ti­gate every­thing from the births and evo­lu­tions of galax­ies to the dis­tri­b­u­tion of dark mat­ter and prop­a­ga­tion of grav­i­ta­tion­al waves through space.” Its data could also help astronomers “find the sources of grav­i­ta­tion­al wave sig­nals detect­ed on Earth, because these faint rip­ples in the very fab­ric of space and time wash over our plan­et after trav­el­ing for mil­lions of light years.” Even if you’re under­tak­ing no such search­es of your own, a trip through the SGA can still enhance your appre­ci­a­tion of how much human­i­ty has come to learn about these “near­by” galax­ies — and how much remains to be learned about all those that lie beyond. Enter the archive here.

Relat­ed con­tent:

The Atlas of Space: Behold Bril­liant Maps of Con­stel­la­tions, Aster­oids, Plan­ets & “Every­thing in the Solar Sys­tem Big­ger Than 10km”

When Galax­ies Col­lide

What Would It Be Like to Fly Through the Uni­verse?

10,000 Galax­ies in 3D

Lux Aeter­na: A Jour­ney of Light, From Dis­tant Galax­ies to Small Drops of Water

NASA Releas­es a Mas­sive Online Archive: 140,000 Pho­tos, Videos & Audio Files Free to Search and Down­load

Based in Seoul, Col­in Marshall writes and broad­casts on cities, lan­guage, and cul­ture. His projects include the Sub­stack newslet­ter Books on Cities, the book The State­less City: a Walk through 21st-Cen­tu­ry Los Ange­les and the video series The City in Cin­e­ma. Fol­low him on Twit­ter at @colinmarshall or on Face­book.

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