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Is there a Black Hole in Our Backyard? · Star Trails: From Backyard Astronomy to Cosmic Wonder

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Howdy Star Gazers and welcome to this episode
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of Star Trails. My name is Drew, and I'll be
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your guide to the night sky for the period of
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July the 5th through the 18th. This week we explore
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a wild theory. Maybe Planet Nine isn't an object
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in the outer reaches of our solar system. but
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a strange relic of the very early universe known
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as a Primordial Black Hole. Science supports
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their existence, but actually finding one may
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be like searching for a needle in a haystack,
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if that haystack was thousands of miles wide
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and the needle was invisible. Later in the show,
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we'll celebrate an upcoming new moon with a look
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at what you can expect to see in the night sky.
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And keep in mind, we're still on our summer publishing
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schedule, so through August, new episodes drop
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every two weeks. If you're a new listener, you
1:02
may enjoy looking through the back catalog. And
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be sure to check out the show website, StarTrails
1:08
.Show. Hit the Start Here link up top for a list
1:12
of my favorite shows and resources for astronomers.
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Whether you're tuning in from the backyard or
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the balcony, I'm glad you're here. So grab a
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comfortable spot under the night sky and let's
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get started. For centuries, we've imagined the
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solar system as something finished. Eight planets,
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a few dwarf planets, asteroids, comets, case
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closed. We put it on classroom posters, memorize
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the order of the planets, and move on. But nowadays,
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we think that map may not be quite complete.
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And the math seems to confirm it. It's a tale
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we've heard before. In the early 1800s, astronomers
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noticed that Uranus wasn't behaving exactly as
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expected. Its orbit seemed to be just a little
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off, as though something unseen was tugging on
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it. Rather than assuming the calculations were
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wrong, two mathematicians working independently
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reached a bold conclusion. There had to be another
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planet farther from the sun. Using nothing more
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than Newton's laws of gravity, they predicted
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where that unseen planet should be. When astronomers
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turned their telescopes toward the predicted
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location, they found Neptune, almost exactly
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where the math said it would be. It's one of
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the greatest detective stories in science, and
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it's had a few sequels. If one unseen planet
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could reveal itself through gravity alone, could
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there be another? For decades, astronomers searched
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for a mysterious planet X lurking beyond Neptune.
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That search eventually led to Clyde Tombaugh's
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discovery of Pluto in 1930. For a time, some
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thought the mystery had been solved. But Pluto
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turned out to be much too small. It simply doesn't
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have enough gravity to account for the strange
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motions astronomers had hoped to explain. As
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the years passed, we found more distant worlds,
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icy bodies inhabiting a vast region beyond Neptune
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known as the Kuiper Belt. Eris, Haumea, Makimaki,
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Sedna. All fascinating discoveries, yet none
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of these objects seem to be the answer. Today,
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the mystery has returned under a different name,
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Planet Nine. Several of the most distant known
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objects in our solar system follow oddly clustered,
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elongated orbits. It's almost as if something
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massive and unseen is quietly shepherding them
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from the darkness, hundreds of times farther
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from the sun than Earth. Some astronomers believe
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these unusual orbits continue to point toward
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a large, undiscovered planet. Others argue the
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apparent pattern may simply be the result of
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observational bias. In other words, we've only
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found the objects our surveys are most likely
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to detect. But recently, a far stranger possibility
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has entered the conversation. What if Planet
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9 isn't a planet at all? What if the invisible
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object tugging at the edge of our solar system
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is something that has been wandering the cosmos
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since almost the beginning of time? A tiny black
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hole. Not the remains of a dead star, but a relic
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from the birth of the universe itself. The words
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black hole always conjure up a certain image.
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Maybe you picture a dying star collapsing in
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on itself. Maybe you imagine a swirling disk
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of glowing gas disappearing into a dark abyss.
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Or maybe you've seen one of those famous artist
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renderings where light itself bends around a
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pitch black sphere. And ordinarily, you'd be
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right. Most of the black holes we know about
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began their lives as stars. Massive stars live
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fast, burn through their nuclear fuel, and when
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they die, gravity wins. Their cores collapse
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into objects so dense that not even light can
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escape. And those are called stellar black holes.
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But what if I told you there may be another kind
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altogether? To understand them, we have to travel
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back almost 13 .8 billion years. to a time before
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there were stars, galaxies, or planets. The early
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universe wasn't filled with suns and worlds.
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It was an unimaginably hot, dense sea of energy
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and particles. Matter hadn't assembled into the
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grand cosmic structures we see today. Everything
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was compressed into a universe so young that
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time itself had barely begun ticking. Now imagine
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that this newborn universe wasn't perfectly smooth.
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Imagine tiny wrinkles, regions where the density
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happened to be just a little higher than the
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space around them. Some theoretical models suggest
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that under just the right conditions, a few of
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those regions could have collapsed under their
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own gravity almost immediately. Instead of forming
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from the death of a star, these black holes would
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have been born directly from the chaos of the
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Big Bang itself. Astronomers call them primordial
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black holes. If they exist, they would be among
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the oldest objects in the universe. Let's put
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that into perspective. Our sun is about four
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and a half billion years old. Earth formed shortly
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afterward. The dinosaurs appeared only a couple
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hundred million years ago. Human civilization
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is barely a blink of an eye. But a primordial
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black hole could have existed before the very
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first star ever lit up the universe. Now here's
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the part that really stretches the imagination.
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When we hear the words black hole, we tend to
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think big. But black holes aren't defined by
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their size. They're defined by their mass. If
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you could somehow compress the mass of several
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Earths into an object no larger than a bowling
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ball, gravity would take over completely. the
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object would become a black hole. Its mass wouldn't
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change, its gravity wouldn't change, only its
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size. It's one of the strangest ideas in all
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of physics, an object carrying the mass of multiple
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worlds hidden inside something you could almost
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hold in your hands, even though getting too close
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to it would instantly become the last mistake
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you ever made. Now, I've been watching a lot
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of professional bowling on TV lately for some
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reason, so the idea that the mass of three or
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more earths could be crammed into something you
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could chuck down a bowling lane is intriguing.
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By the way, that ball would weigh, oh, about
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18 septillion kilograms or so. That's an 18 with
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24 zeros behind it. The pins wouldn't have a
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chance, and neither would anything else near
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it. But, back to the mystery at the edge of our
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solar system. Could something that ancient, compact,
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and invisible be quietly orbiting the sun hundreds
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of astronomical units away, revealing itself
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only through its gravity? So let's suppose, just
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for a moment, that there really is a primordial
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black hole lurking in the outer solar system.
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How would we ever find it? After all, that's
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the whole problem with black holes. They're black.
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They don't shine like stars. They don't reflect
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sunlight like planets. You can't simply point
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a telescope toward the darkness and wait for
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one to drift into view. Instead, astronomers
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have to become detectives. Of course, the evidence
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they collect isn't fingerprints. It's gravity.
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Gravity is invisible, but it leaves clues because
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we can see its effects. It's the reason planets
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orbit the Sun, it's the reason our moon circles
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Earth, and it's the reason entire galaxies hold
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together. If an unseen object has enough mass,
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it announces its presence by tugging ever so
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slightly on everything around it. That's exactly
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how Neptune was discovered, and it's exactly
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why astronomers are still searching for Planet
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Nine today. The distant icy worlds beyond Neptune
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aren't scattered randomly through space. Several
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of the most extreme objects we've discovered
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seem to share oddly elongated, similarly oriented
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orbits. It's as though something massive has
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spent millions of years gently nudging them into
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place. Picture leaves floating on the surface
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of a pond. You never see the fish swimming beneath
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them, but if all the leaves suddenly drift in
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the same direction, You know something underneath
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the surface must be moving. That's the kind of
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evidence astronomers are studying. They're not
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looking at the invisible object itself, but rather
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the ripples it leaves behind. We've found thousands
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of planets orbiting distant stars without ever
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seeing most of them directly. Instead, we watch
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the parent star wobble ever so slightly under
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the pull of an unseen planet. Sometimes we detect
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a tiny dip in a star's brightness as an invisible
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world passes in front of it. We've mapped enormous
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reservoirs of dark matter, not because anyone
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has seen dark matter, but because galaxies rotate
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far too quickly to be held together by visible
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matter alone. Even many of the black holes we
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know about were discovered because they were
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feeding on nearby gas or pulling on companion
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stars. But here's where the primordial black
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hole idea becomes even stranger. A planet reflects
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sunlight. Even if it's dim, eventually a powerful
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enough telescope might spot it. A primordial
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black hole, on the other hand, reflects nothing.
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There would be no disk, no atmosphere, no clouds,
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no sunlight glinting from an icy surface. Just
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darkness. If one really is orbiting far beyond
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Neptune, it would be among the most elusive objects
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we could possibly imagine. And yet, even perfect
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darkness can't hide from gravity. If Planet 9
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is a planet, then sooner or later someone should
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find it. It may be incredibly faint, it may take
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years of searching with the largest telescopes
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on Earth, but planets reflect sunlight, however
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dimly they can eventually give themselves away.
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A primordial black hole is another matter entirely.
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You could point the world's largest telescope
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directly at it and see nothing. So astronomers
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have begun thinking about different kinds of
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evidence. One possibility is gravitational lensing.
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According to Einstein's theory of gravity, mass
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bends space itself. When light from a distant
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star passes near a very massive object, that
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light doesn't travel in a perfectly straight
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line. Instead, it follows the curved shape of
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space around the object. The result is a tiny
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distortion. A distant background star might briefly
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appear brighter, or its apparent position might
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shift ever so slightly. It's almost as though
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the invisible object acts like a cosmic magnifying
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glass. Astronomers have already used this technique
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to discover otherwise invisible objects throughout
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our galaxy. Perhaps one day it could reveal something
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hidden much closer to home. Then there's an even
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stranger possibility. Some physicists have suggested
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that if dark matter exists as certain hypothetical
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particles, those particles might collect around
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a primordial black hole over billions of years.
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If enough of them gathered together, they could
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occasionally collide and annihilate one another,
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producing bursts of high -energy gamma rays.
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In other words, we wouldn't be seeing the black
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hole itself, we'd be seeing a glowing cloud of
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exotic particles surrounding something that's
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completely invisible. Now, to be clear, none
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of this has been observed. No primordial black
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hole has ever been confirmed. No mysterious gamma
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ray beacon has ever been linked to one, and Planet
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Nine itself remains hypothetical. And this is
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science working exactly the way it's supposed
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to. Someone has a theory, and science asks the
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hard questions. Whether Planet Nine turns out
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to be a distant ice giant, a primordial black
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hole, or nothing at all, the search itself is
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teaching us new ways to investigate an invisible
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universe. New observatories like the Vera C.
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Rubin Observatory, which just came online last
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week, will repeatedly photograph the entire southern
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sky, creating an unprecedented time -lapse record
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of the universe. Tiny changes in the positions
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and brightness of millions of objects may reveal
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clues we've never had before. Space telescopes
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continue mapping the motions of stars with extraordinary
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precision, while high energy observatories keep
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watch for mysterious bursts of gamma rays. Gravitational
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lensing surveys search for objects that reveal
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themselves only through their gravity. None of
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these observatories were built specifically to
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find primordial black holes, but they may be
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exactly the tools that finally tell us whether
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such objects exist. Maybe someday those observations
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will reveal a massive planet hiding in the darkness
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beyond Neptune. Maybe they'll tell us there's
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nothing there at all. Or maybe they'll uncover
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something stranger. A tiny relic from the first
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fraction of a second after the Big Bang. Quietly
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orbiting the Sun for billions of years without
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reflecting a single ray of light. Whatever the
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answer turns out to be, it's a comforting reminder
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that we still don't know everything about our
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own cosmic neighborhood. Out beyond the familiar
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planets, there are still blank spaces. And history
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has shown us that blank spaces on a map are often
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where the greatest discoveries are waiting. After
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a quick break, we'll be back with a look at what
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you can expect to see in the night sky in the
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coming weeks. Stay with us. Welcome back. Now
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let's take a look at what's happening in the
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night sky over the next couple of weeks. The
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big headline this period is the moon. We'll begin
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under a waning moon, which means darker skies
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return with each passing night, culminating in
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the new moon on Tuesday, July the 14th. That's
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the best opportunity this month to hunt down
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faint galaxies, nebula, and the rich star clouds
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of the summer Milky Way. If you have access to
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a truly dark location, take advantage of those
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moonless evenings around July the 13th through
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the 16th. The Milky Way stretches dramatically
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from the southern horizon through the Summer
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Triangle overhead, making this one of the finest
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times of the year simply to lie back in a lawn
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chair and soak in our galaxy. Speaking of the
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Summer Triangle, Vega, Deneb, and Altair now
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dominate the evening sky. If you're looking for
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a challenge with binoculars, scan the area between
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Cygnus and Vulpecula for the famous Coathanger
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Asterism, a delightful little pattern that isn't
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actually a star cluster, but always seems to
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surprise first -time observers. Turning to the
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planets, Saturn continues to improve in the pre
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-dawn sky. Look toward the east after midnight
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or before sunrise, where the ringed planet shines
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steadily above the horizon. On the mornings of
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July 7th and 8th, a waning moon slides close
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to Saturn creating a beautiful pairing that's
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easy to spot with the naked eye. Nearby, you'll
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also find Mars and the Pleiades star cluster
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joining the scene before dawn. If you have good
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binoculars or a telescope, look between the Pleiades
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and Mars to find Uranus. Mars itself is still
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fairly modest in brightness, but it's slowly
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climbing into a better observing position as
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we move through the second half of the year.
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If you're up before sunrise, it's worth following
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its progress from week to week. Jupiter, our
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companion through the winter, spring, and early
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summer, has wandered across the sky and now joins
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Mercury close to the setting Sun. Both will be
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virtually impossible to spot during this period.
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As we approach the new moon, keep an eye on the
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western horizon after sunset. On July the 17th,
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a razor thin crescent moon appears alongside
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brilliant Venus, creating one of the prettiest
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naked eye sights of the month. Bring along a
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pair of binoculars and you may even notice earth
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shine, that soft glow illuminating the moon's
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dark side caused by sunlight reflected from our
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own planet. Deep sky observers should make the
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most of these moonless nights. This is prime
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season for the Great Hercules Cluster M13, one
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of the finest globular clusters in the Northern
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Hemisphere. Just east of it lies the Ring Nebula
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in Lyra, a favorite target for small telescopes.
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Farther south, the rich star fields of Sagittarius
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are packed with open clusters and glowing nebula
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waiting to be explored. Meteor activity is beginning
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to wake up as well. The southern delta aquarids
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officially become active around July the 12th,
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although their peak won't arrive until the end
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of the month. You might catch an early meteor
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or two during the dark, moonless mornings after
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the new moon, which is a nice preview of showers
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later this summer. That's going to do it for
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this week. If tonight's episode sparked your
20:21
curiosity or maybe gave you something to think
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about the next time you look up, I'd be honored
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if you shared Star Trails with someone who might
20:29
enjoy the journey. You can always find the latest
20:32
episodes, show notes, and extras at StarTrails
20:36
.Show. And if you'd like to help support the
20:39
show, there's also a little Buy Me a Coffee link
20:41
on the site. That genuinely helps keep these
20:44
stories coming. Be sure to follow Star Trails
20:47
on Blue Sky and YouTube. Links are in the show
20:51
notes. Until we meet again beneath the stars,
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clear skies everyone.