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    Download
    00:00:01
    what if I told you that there is a
    00:00:03
    colossal structure that begins at the
    00:00:06
    edge of our solar
    00:00:09
    system one that encircles our sun and
    00:00:12
    all of the planets but we've never seen
    00:00:15
    it a shell made up of billions or even
    00:00:19
    trillions of ancient icy chunks the size
    00:00:22
    of mountains marks the outermost
    00:00:25
    boundary of our solar system or so we
    00:00:28
    think
    00:00:32
    jaw-droppingly far away beyond the reach
    00:00:35
    of even our most powerful telescopes the
    00:00:38
    O cloud is a region shrouded in mystery
    00:00:41
    and speculation where the sun's
    00:00:43
    influence grows faint as it brushes up
    00:00:46
    against the void of interstellar space
    00:00:49
    what exactly is this art cloud if we've
    00:00:53
    never directly observed it how do we
    00:00:56
    know it's out there and why do some
    00:00:59
    people question its
    00:01:01
    existence let's find out I'm Alex Mogan
    00:01:05
    and you're watching astrom join me today
    00:01:07
    as we venture to the farthest reaches of
    00:01:10
    our solar system and beyond to construct
    00:01:13
    an image of this unseen astronomical
    00:01:18
    Wonder you've probably heard of the
    00:01:21
    asteroid belt and maybe even the Kyper
    00:01:23
    belt at two different locations in our
    00:01:26
    solar system these roughly donut-shaped
    00:01:29
    bands of De each move in the same
    00:01:31
    direction and more or less on the same
    00:01:34
    orbital plane as the planets around our
    00:01:36
    sun the asteroid belt is the closest to
    00:01:39
    the Sun of these two debris Rings
    00:01:41
    located between Mars and Jupiter and
    00:01:44
    consists of millions of orbiting
    00:01:47
    asteroids the Kyer Bel on the other hand
    00:01:50
    was first proposed by astronomer jirard
    00:01:52
    Kyer as the origin of Short period
    00:01:55
    comets in the mid 20th century it is a
    00:01:58
    massive field of icy debris out past
    00:02:01
    Neptune occasionally a piece of Kyper
    00:02:03
    belt debris will get pushed by gravity
    00:02:06
    sending it on a new orbit closer to the
    00:02:08
    Sun in some cases this creates a new
    00:02:12
    short period Comet these comets have
    00:02:15
    orbits of less than 200 years and are
    00:02:17
    often predictable as they continue to
    00:02:19
    make subsequent orbits around the Sun at
    00:02:22
    the same time that Kyer was
    00:02:24
    investigating short period comets a
    00:02:26
    Dutch astronomer named Yan ort was
    00:02:29
    contemplating the origin of long period
    00:02:32
    comets few scientists of the 20th
    00:02:34
    century made more contributions to
    00:02:37
    astronomy than art in 1927 he calculated
    00:02:41
    our place in the Milky Way galaxy and in
    00:02:44
    1932 he was the first to find evidence
    00:02:47
    of dark matter to name a few examples of
    00:02:50
    his discoveries in 1950 or was the first
    00:02:55
    to theorize the existence of a thick
    00:02:57
    bubble of swarming icy debris that
    00:03:00
    surrounded our entire solar system now
    00:03:03
    known as the OD Cloud but unlike the
    00:03:06
    asteroid belt and Hyper belt it's still
    00:03:09
    yet to be directly
    00:03:11
    observed to understand this Theory let
    00:03:14
    me explain what led or to this
    00:03:18
    proposition unlike comets with short
    00:03:21
    orbits such as Hal's Comet with an
    00:03:23
    average period of 75.3 years or Comet
    00:03:28
    Anka with a period of just 3.3 years
    00:03:31
    long period comets were
    00:03:34
    unpredictable for one thing their
    00:03:36
    orbital periods were so long that in
    00:03:39
    some cases they could take as many as 30
    00:03:42
    million years to complete one orbit and
    00:03:47
    curiously these comets came from all
    00:03:49
    different directions and had various
    00:03:52
    orbital
    00:03:53
    inclinations it was a mystery on the
    00:03:56
    grandest of scales but W noticed a few
    00:03:59
    things that all of these long period
    00:04:02
    comets had in
    00:04:04
    common their orbits indicated that these
    00:04:07
    comets weren't coming from far out in
    00:04:09
    interstellar space but that their origin
    00:04:12
    had to be closer to home however as I'll
    00:04:15
    explain in a moment not too close to
    00:04:18
    home so if these long period comets
    00:04:21
    weren't coming from the Kyper belt and
    00:04:23
    weren't coming from far out in
    00:04:25
    interstellar space where were they
    00:04:28
    coming from
    00:04:30
    or Found A peculiar similarity among the
    00:04:33
    orbits of these comets one that might
    00:04:35
    provide the answer to that
    00:04:38
    question the point in a comet orbit
    00:04:41
    where it is most distant from the Sun is
    00:04:43
    called the aelon or notice that all
    00:04:46
    observed long period comets seem to have
    00:04:48
    an aelon that all grouped around a
    00:04:51
    certain distance around 7.5 trillion
    00:04:55
    kilm from the Sun that's right trillion
    00:04:58
    with a t
    00:05:01
    as you can see when it comes to the
    00:05:03
    distances I'll be talking about in this
    00:05:05
    video our typical units of measurement
    00:05:07
    fall a bit short so instead of using
    00:05:10
    kilometers I will switch to astronomical
    00:05:13
    units one astronomical unit or Au is
    00:05:17
    defined as the distance between Earth
    00:05:19
    and the Sun or about 150 million kilm so
    00:05:24
    Earth is One AU from the Sun the aelia
    00:05:27
    grouping that art noticed where the long
    00:05:30
    period comets reached their farthest
    00:05:32
    orbital distance from the Sun was about
    00:05:36
    50,000 astronomical units to help
    00:05:39
    picture the orbits of these long period
    00:05:41
    comets keep in mind that the outermost
    00:05:44
    planet in our solar system Neptune is
    00:05:47
    around 30 AU from the Sun or about 4.5
    00:05:51
    billion km the main region of the Kyper
    00:05:54
    belt extends from Neptune's orbit at 30
    00:05:57
    Au out to around 50 AU but recent
    00:06:00
    evidence from NASA's new horizon
    00:06:02
    spacecraft suggests a second region of
    00:06:04
    the Kyo belt called the scattered disc
    00:06:07
    which continues to around 1,000 Au it's
    00:06:11
    with these key findings from observed
    00:06:13
    comets that they didn't come from far
    00:06:15
    out in interstellar space the orbital
    00:06:17
    distances clustered around 50,000 Au and
    00:06:21
    the fact that they arve from any
    00:06:22
    direction and orbital inclination that
    00:06:25
    or theorized a special spherical swarm
    00:06:28
    of icy Dey that he believed to be the
    00:06:31
    origin of long period comets in the
    00:06:34
    years since then mathematical models
    00:06:36
    have shown agreement with the OD Cloud
    00:06:39
    Theory and astronomers have further
    00:06:41
    theorized various mechanics by which the
    00:06:43
    OD Cloud came to be in this current
    00:06:46
    state the leading idea is that the OD
    00:06:49
    Cloud formed from ancient Deb leftovers
    00:06:52
    from when our planet formed 4.6 billion
    00:06:54
    years ago after the planets formed the
    00:06:57
    surrounding area was still rich with
    00:06:59
    smaller left over chunks of material
    00:07:02
    called
    00:07:03
    planetesimals the Gravity from these
    00:07:05
    early planets then scattered the left
    00:07:07
    over material in every direction some
    00:07:10
    material was flung out of the solar
    00:07:12
    system entirely but a significant
    00:07:15
    portion was sent into seemingly random
    00:07:18
    eccentric orbits around the Sun these
    00:07:21
    scattered planetesimals had eccentric
    00:07:23
    enough orbits that they were influenced
    00:07:25
    by gravitational forces outside of our
    00:07:28
    solar system while still remaining
    00:07:30
    captured in our sun's orbit and it's
    00:07:32
    believed that this is how these billions
    00:07:35
    or trillions of icy chunks came to be
    00:07:38
    part of the OD
    00:07:39
    Cloud gravitational pertubations can
    00:07:42
    force Kyper Bel objects out of place
    00:07:45
    creating short period
    00:07:47
    comets we think that similar forces are
    00:07:51
    what send or Cloud objects into
    00:07:53
    elliptical orbits with the sun thereby
    00:07:56
    creating long period comets these
    00:07:59
    perturbations could be caused by passing
    00:08:02
    stars or molecular clouds or tidal
    00:08:05
    forces from the Milky Way itself in fact
    00:08:09
    about 70,000 years ago Schultz's star
    00:08:12
    gained the title of the star that came
    00:08:14
    closest to our solar system actually
    00:08:17
    grazing the outer region of the or Cloud
    00:08:20
    but luckily for us it didn't cause any
    00:08:23
    catastrophic disruptions to the or cloud
    00:08:26
    or our solar system at large Schultz's
    00:08:29
    star is a low mass binary system made up
    00:08:32
    of a red dwarf and a brown dwarf
    00:08:34
    companion so 10 Millennia ago even at a
    00:08:38
    much closer distance to the or Cloud the
    00:08:40
    gravitational influence of this binary
    00:08:42
    star was significantly weaker than that
    00:08:45
    of our much more massive
    00:08:47
    Sun however While most objects experienc
    00:08:51
    little to no impact during the low mass
    00:08:53
    star's brief encounter with the edge of
    00:08:55
    the or Cloud numerical simulations from
    00:08:58
    2018 concluded that Schult star is
    00:09:01
    believed to have nudged at least some
    00:09:03
    objects out of place creating and
    00:09:05
    influencing the trajectory of some long
    00:09:08
    period
    00:09:10
    comets but the sun has been around for
    00:09:12
    over 4 billion years and that's a lot of
    00:09:15
    time for other close encounters with
    00:09:16
    stars in the distant past could these
    00:09:19
    interactions have prevented the OD cloud
    00:09:21
    from forming our models suggest
    00:09:25
    no however OD Cloud material may get
    00:09:28
    exchanged Ed with passing Stars over
    00:09:31
    eons you see other more recent numerical
    00:09:35
    simulations have suggested that or
    00:09:38
    clouds could exist around other stars
    00:09:41
    too our or Cloud may also have both an
    00:09:45
    inner and an outer region each with its
    00:09:48
    own distinct shape some scientists
    00:09:51
    suggest that the inner region may be
    00:09:53
    more like a disc similar to the donut
    00:09:55
    shape of the Kyper belt while the outer
    00:09:58
    region is suggested to form the
    00:09:59
    spherical shell more widely associated
    00:10:02
    with the or Cloud altogether the inner
    00:10:05
    edge of this two region or Cloud maybe
    00:10:08
    2,000 astronomical units from the Sun at
    00:10:10
    its closest with the far Edge stretching
    00:10:14
    all the way out into Interstellar space
    00:10:17
    potentially reaching as far as 100,000
    00:10:21
    astronomical units from the center of
    00:10:23
    our solar system this means the or Cloud
    00:10:27
    could extend more than 1 5 light years
    00:10:31
    across to put that into perspective
    00:10:34
    since we're talking about very very
    00:10:36
    large distances consider Voyager 2
    00:10:39
    spacecraft for a moment as of the
    00:10:41
    publication of this video Voyager 2 has
    00:10:44
    traveled to a distance of about
    00:10:47
    139 astronomical units from the Sun
    00:10:50
    since its launch from Earth at 1 Au in
    00:10:53
    August of
    00:10:54
    1977 that's about 3.3 Au per year or
    00:10:58
    about 56,000
    00:11:00
    kmph it's the second farthest human-made
    00:11:03
    object in space just after Voyager
    00:11:06
    1 in August 2007 Voyager 2 passed beyond
    00:11:11
    the boundary of the heliosphere the
    00:11:13
    outermost layer of the sun's atmosphere
    00:11:16
    it extends out beyond the planets and
    00:11:19
    three times further than the distance to
    00:11:21
    Pluto outside of the heliosphere the
    00:11:24
    sun's constant flow of charged particles
    00:11:26
    called the solar wind is finally impeded
    00:11:29
    by the interstellar medium and in
    00:11:31
    November 2018 Voyager 2 finally crossed
    00:11:35
    the final layer of solar turbulence
    00:11:37
    called The Helio sheath and continued on
    00:11:40
    into Interstellar
    00:11:43
    space despite passing beyond the
    00:11:46
    heliosphere and well past the main Kyper
    00:11:49
    belt Voyager 2 would still need to
    00:11:52
    travel for another 300 or so years just
    00:11:55
    to reach the innermost edge of the or
    00:11:58
    cloud that's how far away it is and to
    00:12:02
    fly through the or Cloud that could take
    00:12:06
    another 30,000 years even when traveling
    00:12:10
    at 56,000
    00:12:13
    kmph it still takes all that time just
    00:12:16
    to travel around 1 and a half light
    00:12:18
    years if you've ever wondered why
    00:12:21
    Interstellar or Intergalactic space
    00:12:22
    travel is difficult keep in mind that
    00:12:25
    our nearest Stellar neighbor is Proxima
    00:12:28
    centor at around 4.25 light years
    00:12:32
    away however some still question the
    00:12:35
    existence of the or Cloud mainly because
    00:12:38
    we're unable to directly observe it
    00:12:41
    another argument has been made that long
    00:12:43
    period comets may come from other places
    00:12:45
    such as Interstellar space and in fact
    00:12:47
    the first observation of an Interstellar
    00:12:50
    Comet one that had Origins from outside
    00:12:53
    our Sun's influence was made in 2019 by
    00:12:56
    amateur astronomer genady borisov
    00:13:00
    professional astronomers joined in to
    00:13:01
    collect data on Comet borisov named
    00:13:04
    after its first Observer they found an
    00:13:06
    unusual composition a higher
    00:13:09
    concentration of carbon monoxide than
    00:13:11
    the average Comet originating from our
    00:13:13
    own solar system suggesting that this
    00:13:15
    Comet may have formed in the presence of
    00:13:17
    a red dwarf a different type of star
    00:13:20
    than our sun and yet the vast majority
    00:13:23
    of astronomers agree that the or cloud
    00:13:25
    is really out there despite the fact
    00:13:28
    that we've never laid eyes on
    00:13:30
    it plenty of indirect observations and
    00:13:33
    mathematical models show great support
    00:13:36
    for the theory and the evidence
    00:13:37
    continues to add up but why is it
    00:13:40
    exactly that we've never been able to
    00:13:42
    see the old Cloud after all with
    00:13:45
    telescopes we can see stars far beyond
    00:13:47
    our own solar system and even the shapes
    00:13:50
    of distant
    00:13:51
    galaxies the difference is size and
    00:13:55
    light think about it a piece of or Cloud
    00:13:58
    debris is rough the size of one mountain
    00:14:00
    on Earth let's consider Mount Everest at
    00:14:03
    around 9 km tall now consider the or
    00:14:06
    clouds innermost boundary begins
    00:14:08
    somewhere around 3,000 Au or roughly 450
    00:14:12
    million km from the Sun the distance
    00:14:15
    from the sunand to the nearest piece of
    00:14:17
    or Cloud debris is 50 million times the
    00:14:20
    size of the debris talk about looking
    00:14:23
    for a needle in a Hast deack but more
    00:14:27
    crucially even is that stars and
    00:14:29
    galaxies give off light but OD debris
    00:14:32
    does not the planets are relatively
    00:14:35
    close to the Sun so they are able to
    00:14:37
    reflect the Sun's light and therefore
    00:14:39
    are visible likewise the asteroid belt
    00:14:42
    and even the Kyper belt are close enough
    00:14:44
    to the Sun that we can use telescopes to
    00:14:47
    directly observe their debris but
    00:14:49
    outside of the heliosphere the cloud is
    00:14:52
    just too far and too dark for our
    00:14:55
    telescopes to catch a glimpse despite
    00:14:58
    the or clouds our gantan footprint and
    00:15:00
    pivotal role in shaping our
    00:15:02
    understanding of the origin of many long
    00:15:04
    period comets for now we can still only
    00:15:07
    infer its existence through mathematical
    00:15:09
    models and indirect observation but
    00:15:13
    don't let our inability to make direct
    00:15:15
    observations discourage you from
    00:15:17
    following the evidence I can think of a
    00:15:19
    few other times in history when
    00:15:21
    scientists put forth Monumental theories
    00:15:23
    despite a lack of direct observation for
    00:15:26
    example in the 16th and 17th century CES
    00:15:29
    respectively cernus and Galileo put
    00:15:32
    forth the theory that the planets
    00:15:34
    orbited around the Sun contradicting a
    00:15:37
    widely held belief at the time that the
    00:15:39
    Earth was the center of the solar
    00:15:41
    Universe their theory of a heliocentric
    00:15:44
    solar system was not based on Direct
    00:15:46
    observation but rather on indirect
    00:15:49
    observation of the orbit of the planets
    00:15:52
    as we know that theory turned out to be
    00:15:55
    spoton that's the thing I love about
    00:15:58
    science and the pursuit of knowledge
    00:16:00
    there's always more to learn the farther
    00:16:02
    we travel through time the better our
    00:16:05
    understanding of the solar system will
    00:16:06
    get who knows maybe in 100 years future
    00:16:10
    astronomers will have found a way to
    00:16:12
    prove the existence of the or Cloud once
    00:16:14
    and for all or maybe they'll have found
    00:16:16
    a whole new explanation for long period
    00:16:19
    comets until then the all Cloud remains
    00:16:22
    one of astronomies most compelling
    00:16:24
    enigmas
    00:16:27
    [Music]
    00:16:29
    thanks for watching this video was in
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    description once again a huge thank you
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    from myself and the whole astrom
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    team meanwhile click the link to this
    00:17:12
    playlist for more astrom content I'll
    00:17:15
    see you next time

    Description:

    This video is a part of a series looking at the Outer Solar System. The Oort Cloud is believed to be a vast cosmic shell at the edge of our Solar System that astronomers have never directly seen. The colossal structure contains trillions of icy bodies and stretches nearly a light-year radius from our Sun, taking light weeks to reach its inner edge. Within, ancient chunks of ice larger than mountains drift in endless orbits, occasionally disturbed by passing stars that send them plunging toward the inner solar system as comets and potential hazards to Earth. So if no one has ever seen it, how do we know it even exists? In addition to a general overview of the Oort Cloud, I’ll address the reasons why some scientists question its existence. ▀▀▀▀▀▀ 0:00 Does the Oort Cloud exist? 1:18 Solar system debris 3:20 Observing comets 6:47 How did the Oort Cloud form? 8:08 Visit from another star 9:42 How far away is the Oort Cloud? 12:33 Grounds for suspicion 13:39 Why can’t we see it? 14:57 Up for debate ▀▀▀▀▀▀ To stay on top of space news, sign up to the Astrum newsletter: https://astrumspace.kit.com/ Astrum Displate Posters: https://displate.com/artist/astrumspace?art=5f04759ac338b Astrum Merch: https://astrum-shop.fourthwall.com/ Join us on the Astrum discord: https://discord.com/invite/TKw8Hpvtv8 A huge thanks to our Patreons who help make these videos possible. Sign-up here to support the channel: https://www.patreon.com/astrumspace ▀▀▀▀▀▀ Astrum Podcast on Spotify: https://open.spotify.com/show/6jPRrbq3o3dpvBb173ZTKi Astrum Earth: https://www.youtube.com/@AstrumEarth Astrum Extra: https://www.youtube.com/@astrumextra Astrum Spanish: https://www.youtube.com/@astrumespanol Astrum Portuguese: https://www.youtube.com/channel/UChn_-OwvV63mr1yeUGvH-BQ ▀▀▀▀▀▀ Credits: Writer: Michelle Babcock Editor: Frame Forge Thumbnail Designer: Peter Sheppard Channel Manager: Georgina Brenner Executive Producer: Raquel Taylor Creator of Astrum: Alex McColgan With special thanks to: NASA/ESO/ESA

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      http://univideos.ru/ website is the best way to download a video or a separate audio track if you want to do without installing programs and extensions.

      The UDL Helper extension is a convenient button that is seamlessly integrated into YouTube, Instagram and OK.ru sites for fast content download.

      UDL Client program (for Windows) is the most powerful solution that supports more than 900 websites, social networks and video hosting sites, as well as any video quality that is available in the source.

      UDL Lite is a really convenient way to access a website from your mobile device. With its help, you can easily download videos directly to your smartphone.

    question iconWhich format of "The Invisible 1.5 Light-Year Wall Around Our Solar System" video should I choose?arrow icon

      The best quality formats are FullHD (1080p), 2K (1440p), 4K (2160p) and 8K (4320p). The higher the resolution of your screen, the higher the video quality should be. However, there are other factors to consider: download speed, amount of free space, and device performance during playback.

    question iconWhy does my computer freeze when loading a "The Invisible 1.5 Light-Year Wall Around Our Solar System" video?arrow icon

      The browser/computer should not freeze completely! If this happens, please report it with a link to the video. Sometimes videos cannot be downloaded directly in a suitable format, so we have added the ability to convert the file to the desired format. In some cases, this process may actively use computer resources.

    question iconHow can I download "The Invisible 1.5 Light-Year Wall Around Our Solar System" video to my phone?arrow icon

      You can download a video to your smartphone using the website or the PWA application UDL Lite. It is also possible to send a download link via QR code using the UDL Helper extension.

    question iconHow can I download an audio track (music) to MP3 "The Invisible 1.5 Light-Year Wall Around Our Solar System"?arrow icon

      The most convenient way is to use the UDL Client program, which supports converting video to MP3 format. In some cases, MP3 can also be downloaded through the UDL Helper extension.

    question iconHow can I save a frame from a video "The Invisible 1.5 Light-Year Wall Around Our Solar System"?arrow icon

      This feature is available in the UDL Helper extension. Make sure that "Show the video snapshot button" is checked in the settings. A camera icon should appear in the lower right corner of the player to the left of the "Settings" icon. When you click on it, the current frame from the video will be saved to your computer in JPEG format.

    question iconHow do I play and download streaming video?arrow icon

      For this purpose you need VLC-player, which can be downloaded for free from the official website https://www.videolan.org/vlc/.

      How to play streaming video through VLC player:

      • in video formats, hover your mouse over "Streaming Video**";
      • right-click on "Copy link";
      • open VLC-player;
      • select Media - Open Network Stream - Network in the menu;
      • paste the copied link into the input field;
      • click "Play".

      To download streaming video via VLC player, you need to convert it:

      • copy the video address (URL);
      • select "Open Network Stream" in the "Media" item of VLC player and paste the link to the video into the input field;
      • click on the arrow on the "Play" button and select "Convert" in the list;
      • select "Video - H.264 + MP3 (MP4)" in the "Profile" line;
      • click the "Browse" button to select a folder to save the converted video and click the "Start" button;
      • conversion speed depends on the resolution and duration of the video.

      Warning: this download method no longer works with most YouTube videos.

    question iconWhat's the price of all this stuff?arrow icon

      It costs nothing. Our services are absolutely free for all users. There are no PRO subscriptions, no restrictions on the number or maximum length of downloaded videos.