THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
(207) 780-4249 usm.maine.edu/planet
43.6667° N 70.2667° W Founded January 1970
2022-2023: XCIV
Sunrise: 5:14 a.m.
Sunset: 8:01 p.m.
Civil twilight begins: 4:41 a.m.
Civil twilight ends: 8:35 p.m.
Sun's host constellation: Taurus the Bull
Moon phase: Waning crescent (5% illuminated)
Moonrise: 4:07 a.m.
Moonset: 7:17 p.m. (5/18/2023)
Julian date: 2460082.29
"As with anything creative, change is inevitable."
-Enya
THE DAILY ASTRONOMER
Wednesday, May 17, 2023
Living Large in the Early Stelliferous
Astronomers have divided the Universe into five distinct ages, or, if you
prefer, eras:
- the primordial
- the stelliferous
- the degenerate
- the black hole
- the dark
As the titles imply, the Universe passed through a beginning, is moving
through a period of constant star birth (the stelliferous), but will
eventually decline to the point at which even the supermassive black holes
scattered throughout the cold remnants of a dying universe will perish into
oblivion. It is the ultimate example of a celestial Gotterdammerung
in which nature's most magnificent and complex constructs will be cast
asunder for all eternity, which, as its name implies, represents an
interminable time period.
However, before you cue the requiem music and lapse into a state of
hopeless despondency, take heart, for this Stelliferous Era will last a
while. How long will it persist? About 100 trillion years. Yes,
that value is so large as to be completely abstract. Think of it this
way. Our Universe formed about 13.8 billion years ago. The first stars
formed about 200 million years after the cosmos was born. If we compress
the period between the formation of the first stars and the present into
the space of a single week, the entire Stelliferous Era will continue for
another 140 years!
[image:
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*Located 7,000 light years from our solar system, the Eagle Nebula is a
region of active star birth. At this very moment, billions of such nebulae
throughout the Universe are churning out stars at a fantastic rate. Image
credit: NASA/Hubble Institute*
Even though we're living in the earliest part of the Stelliferous, the
cosmos is already cranking out stars at a prodigious rate. Every single
second, 4800 stars ignite. By this statement we mean that every second
4800 protostars manage to ignite and sustain the thermonuclear fusion
reactions that power stars. We add a night sky's worth of stars to the
Universe every 2.2 seconds. Since planet formation seems to be a natural
consequence of star formation, we can assume that tens of thousands of
planets will eventually form around those 4,800 stars.*
[image: arp271_collision.jpg]
*In approximately 4-5 billion years, the Milky Way and Andromeda galaxies
will collide, as is happening with these galaxies within the Arp 271
system. The collision and eventual merger of the Milky Way and Andromeda
galaxies will cause gas clouds within both to compress, precipitating a
furious phase of star birth. Even though this collision will occur in
the far distant future, at the time of their merger, only 0.017% of the
Stelliferous era will have elapsed.*
*Image credit: NASA*
We all know that so much has already transpired throughout time in order to
place us living beings on this one world in orbit around a somewhat average
star. Millions of years to form the solar system; billions of years to
evolve from the earliest prokaryotic cells. And, yet, in Universal terms,
even at the end of the Sun's life cycle six billion years from now, the era
of furious and unrelenting star formation will have only just begun.
*A disquieting corollary to this statement. If only 0.01% of those stars
end up with a life-bearing planet, we'll essentially add 41,472 such life
worlds to the Universe every Earth day.
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