Latest / Star Trails: From Backyard Astronomy to Cosmic Wonder / Under the Same Stars: Ancient Astronomy

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Under the Same Stars: Ancient Astronomy · Star Trails: From Backyard Astronomy to Cosmic Wonder

• 0:07
  Howdy Star Gazers and welcome to this episode
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  of Star Trails. Drew here and I'll be your guide
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  to the night sky for the week starting June the
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  15th through the 21st. This week we'll check
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  in on the moon, a few bright planets, and the
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  rising galactic core. Then we'll take a step
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  back in time to explore how ancient cultures
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  watched and tracked the skies, including the
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  story of a 2 ,000 year old device pulled from
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  a shipwreck that turned out to be the world's
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  first computer. Whether you're tuning in from
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  the backyard, the balcony, or just your imagination,
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  I'm glad you're here. So find a cozy spot, let
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  your eyes adjust, and let's see what the sky
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  holds for us this week. Let's start with the
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  moon, since it tends to dominate our evening
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  sky this week. Tonight the moon is in its waning
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  gibbous phase, about 87 % illuminated, and rises
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  a little after sunset. Each night this week,
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  it'll rise later and later, shrinking as it does.
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  By Wednesday the 18th, it reaches the last quarter,
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  looking like a perfect half -circle in the pre
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  -dawn hours. After that, the moon becomes a waning
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  crescent, rising in the wee hours of the morning
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  and becoming harder to spot as it approaches
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  the new moon on the 25th. One subtle treat arrives
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  on June 23 when the moon reaches Perigee, its
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  closest approach to Earth in its monthly orbit,
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  sitting about 225 ,000 miles away. Perigee also
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  means slightly stronger ocean tides, and for
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  the keen -eyed, a slightly larger lunar disk.
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  The planetary lineup this week spans both dusk
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  and dawn. Right after sunset, the western sky
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  gives us two familiar travelers, Mercury and
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  Mars. Mercury is beginning a brief but favorable
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  evening sight. On the 15th it appears about 74
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  % illuminated through a telescope and shines
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  at magnitude 0 .3, not its brightest, but visible
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  if you've got a clear, flat western horizon.
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  Mercury sets about 90 minutes after the sun,
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  so you'll need to catch it quickly. By June 24th,
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  it'll be part of a neat lineup with the bright
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  Gemini twins, Castor and Pollux, hovering just
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  above the western horizon. If you catch it at
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  twilight, you'll see Mercury sitting below those
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  two stars in a graceful vertical line. A little
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  higher in the sky, Mars is making its slow passage
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  through the constellation Leo. Its orange glow
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  contrasts beautifully with Regulus, Leo's bright
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  blue -white heart star. Look for a close approach
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  with these objects on the 16th and 17th. The
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  pre -dawn sky is where the real planetary action
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  unfolds this week. There you'll find Venus rising
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  brightly in the east about 90 minutes before
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  sunrise. At magnitude negative 3 .9, it's the
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  brightest object in the sky besides the moon
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  and sun. Just to its upper right, you'll find
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  Saturn glowing pale yellow in the constellation
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  Aquarius. On the 19th, the moon will drift nearby
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  Saturn in the early morning sky, creating a gorgeous
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  pre -dawn pairing. If you're up around 3 or 4
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  a .m., it's worth stepping outside for. Jupiter,
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  on the other hand, is making its quiet exit.
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  It's low in the west before dawn and gets lost
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  in the sun's glare by June 24th, when it reaches
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  solar conjunction. That means it's passing directly
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  behind the sun from our point of view. It won't
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  be visible again until it emerges in the morning
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  sky in mid -July. For telescope users, Uranus
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  and Neptune are both technically visible, but
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  they're faint and require effort. Neptune sits
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  near Saturn in the sky this week, though it's
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  at magnitude 7 .9 and invisible without optical
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  aid. Uranus rises before dawn in Aries but remains
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  difficult to spot until it climbs higher in the
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  coming weeks. Now let's pull back from the planets
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  and take in the broader canvas of stars because
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  this time of year the Milky Way really begins
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  to show off. By mid -evening, say around 10 p
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  .m., the Milky Way's bright central band begins
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  to rise in the southeast. If you're under a dark
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  sky free from streetlights and urban haze, you'll
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  see a faint cloudy river of stars running from
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  horizon to zenith. That's the galactic core,
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  and June is one of the best times to see it in
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  the Northern Hemisphere. Overhead, the summer
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  triangle is fully visible. This prominent asterism
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  is formed by three bright stars, Vega in the
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  constellation Lyra, Deneb in Cygnus, and Altair
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  in Aquila. Vega is the brightest of the three
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  and nearly directly overhead. Deneb marks the
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  tail of the celestial swan, and Altair, the eye
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  of the eagle, flaps along the Milky Way's edge.
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  Cygnus, also known as the Northern Cross, is
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  a rich area to explore with binoculars. Look
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  for clusters, dark nebulae, and star clouds tucked
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  along the Milky Way's spine. To the west, Boötes
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  and Arcturus still dominate the early evening.
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  Arcturus is easy to find. Just follow the curve
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  of the Big Dipper's handle and arc to Arcturus.
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  This orange giant star is relatively close, about
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  37 light -years away, and heading towards us.
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  Near Boötes, you'll find Corona Borealis, the
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  northern crown, a small but elegant arc of stars.
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  And rising later in the east, the teapot -shaped
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  Sagittarius begins to ascend, marking the gateway
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  to the galactic center. We're still a few weeks
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  away from any major meteor showers, but sporadic
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  meteors can be seen on any clear night. And with
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  the moon waning towards new this week, darker
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  skies will make these background meteors even
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  easier to spot. The summer solstice occurs on
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  Friday. It's the longest day of the year and
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  the moment when the sun reaches its highest point
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  in the sky. The solstice is a reminder of a truth
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  as old as humanity itself. People have always
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  looked up. Long before telescopes or scientific
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  journals, humans were watching the sky, tracking
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  its rhythms and embedding its stories into stone,
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  memory, and myth. The solstices, both summer
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  and winter, acted as celestial bookmarks for
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  ancient cultures, fixed points in the rhythm
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  of the seasons. From the Arctic Circle to the
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  Andes, they marked time by the sky, planting,
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  harvesting, hunting, and praying according to
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  the movements of the sun, moon, and the stars.
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  Let's begin in prehistoric Europe, where monuments
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  like Stonehenge align almost precisely with the
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  rising sun on the summer solstice. When sunlight
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  breaks over the heelstone and pours into the
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  monument's center, it creates a striking visual
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  that likely held spiritual, agricultural, or
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  communal meaning. Constructed in several phases
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  between roughly 3000 and 2000 BCE, Stonehenge
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  incorporated massive rock formations transported
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  from more than 150 miles away in Wales. Beyond
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  solstice alignments, theories suggest Stonehenge
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  may have functioned as a burial ground, ceremonial
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  center, or a lunar calendar. Similar alignments
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  appear in Ireland and Orkney, where solar events
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  dictate how light enters stone passageways at
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  exact times of year. These early engineers didn't
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  use metal tools or mathematics as we know them,
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  but they built with precision, using horizon
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  markers and the human eye to measure time itself.
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  Across the world in Mesopotamia, the Babylonians
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  were developing what we might recognize as the
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  first scientific astronomy. They recorded the
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  rising and setting of stars, tracked eclipses,
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  and used a base 60 number system that still influences
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  how we measure time today. They also discovered
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  the Saros cycle, an 18 -year period after which
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  lunar and solar eclipses repeat. All of this
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  was done without lenses, telescopes, or even
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  basic optics. Their most sophisticated tools
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  were observation, record -keeping, and patience.
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  But for sheer ingenuity, few artifacts of the
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  ancient world rival the Antikythera mechanism.
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  Pulled from the sea off the coast of Greece in
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  1901, this corroded mass of bronze gears remained
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  a mystery for more than a century. Today, we
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  know it to be an ancient computer. a mechanical
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  device designed around 100 BCE to track the motions
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  of the sun, moon, and five known planets. It
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  even predicted eclipses and synchronized with
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  the Olympic games. Recent studies revealed it
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  used differential gearing and a sophisticated
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  epicyclic model to account for the moon's elliptical
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  orbit. a level of mechanical sophistication not
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  seen again until the 18th century. Its back dials
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  also recorded the metonic cycle, that's a 19
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  -year cycle in which lunar phases recur at the
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  same time, and eclipse predictions using Babylonian
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  -style glyphs. It's the only device of its kind
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  ever found suggesting a lost tradition of high
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  -precision astronomical engineering in the Hellenistic
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  world. The Greeks also gave us some of the earliest
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  theoretical frameworks for understanding the
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  sky. Aristarchus proposed a heliocentric model
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  of the solar system around the 3rd century BCE,
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  nearly 1800 years before Copernicus. Hipparchus,
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  often called the father of trigonometry, developed
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  the first comprehensive star catalog and discovered
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  precession. That's the slow wobble in Earth's
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  axis. And of course Ptolemy's geocentric model,
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  though incorrect, dominated astronomical thought
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  for more than a millennium, owning to its mathematical
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  sophistication and explanatory power. These thinkers
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  were beginning to shift astronomy from observational
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  tradition into formal science. Over in ancient
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  China, astronomers during the Shang dynasty and
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  later eras kept detailed records of comets, eclipses,
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  and planetary motions. They identified guest
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  stars, what we now know as supernova, and connected
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  celestial events to the Emperor's legitimacy.
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  Royal astronomers operated with high stakes.
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  Failing to predict an eclipse would cause political
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  unrest or even cost them their lives. The Chinese
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  were also among the first to document phenomena
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  like Halley's Comet, and their star charts helped
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  preserve sky positions across centuries. In the
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  Inca Empire, solar observation was central to
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  statecraft. Temples like Machu Picchu were aligned
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  with solstices, and ritual pillars were believed
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  to hold the sun in its proper path. Likewise,
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  Mayan kings scheduled battles and ceremonies
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  according to the Venus cycle. The Dresden Codex,
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  one of the few surviving Mayan texts, contains
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  incredibly precise Venus tables. Its appearances
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  and disappearances were used to guide warfare.
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  coronations, and sacrifices. Islamic scholars
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  preserved and expanded on Greek knowledge. They
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  developed astrolabes, improved star catalogs,
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  and calculated planetary orbits with remarkable
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  precision. And speaking of star maps, some of
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  the most astonishing weren't drawn at all. They
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  were sung. The Polynesians, navigating vast stretches
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  of the Pacific, memorized the rising and setting
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  points of stars to guide them between islands
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  that were thousands of miles apart. Without metal
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  tools or written maps, they used oral knowledge,
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  wave patterns, bird behavior, and the stars to
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  sail across the world's largest ocean. Their
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  star compass divided the horizon into more than
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  30 sectors each marked by a key star. This mental
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  map was passed down through chance, ritual, and
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  experience. We also see astonishing sky knowledge
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  in indigenous cultures of North America and Australia.
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  The Navajo, Lakota, and other Native American
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  nations wove constellations into their moral
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  teachings. agricultural cycles, and healing practices.
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  In some traditions, the Milky Way was seen as
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  the path of souls or a great river in the sky.
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  What kind of tools made all this possible? Most
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  ancient astronomers relied on naked eye observation
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  and simple but clever instruments. One such instrument
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  was the nomen, a stick planted vertically in
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  the ground that could track the Sun's shadow
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  to measure time and solstices. Egyptians used
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  plumb lines and the stars to align structures
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  and keep time at night. The armillary sphere,
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  quadrant, and water clocks were used by Greeks,
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  Chinese, and Arabs to refine measurements. Of
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  course, the stars weren't only mapped, they were
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  mythologized. Cultures around the world gave
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  names and stories to the constellations, turning
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  the night sky into a canvas of meaning. The Pleiades,
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  or Seven Sisters, appear in Greek, Japanese,
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  and Aboriginal lore. The Greek version of Orion
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  the Hunter is mirrored in myths from the Americas
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  and Africa, often with similar traits. Chasing.
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  boasting or falling. The Inuit interpret Orion
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  as a caribou hunter. The Greeks imagined Scorpius
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  chasing Orion, which is why they appear on opposite
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  sides of the sky. And the Milky Way itself might
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  be a road, a river, a trail of birds, or the
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  backbone of night, depending on where you're
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  standing. The night sky is part calendar, part
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  compass, and part sacred text. And maybe that's
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  the biggest through line of all. Ancient astronomy
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  wasn't some esoteric discipline. It was life.
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  Watching the sky meant understanding your place
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  in time, your duties to the community, and your
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  connection to something larger than yourself.
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  So today, when we glance at an app to check the
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  phase of the moon or use GPS to navigate a back
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  road, It's easy to forget how deep our relationship
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  with the sky runs. But every time we look up,
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  we're tapping into an ancient tradition. One
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  that crosses borders, bridges millennia, and
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  ties us to the people who built stone circles,
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  carved eclipse charts into clay, or sang the
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  constellations into memory. We're not just watching
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  the sky. We're participating in humanity's oldest
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  shared story. If the stars spoke to you this
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  week, or if a question's been on your mind, I'd
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  love to hear it. Visit our website, StarTrails
• 16:56
  .Show, where you can contact me and explore past
• 17:00
  episodes. Be sure to follow us on Mastodon, Blue
• 17:04
  Sky, and YouTube. Links are in the show notes.
• 17:08
  Until we meet again beneath the stars, clear
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  skies everyone.