Munchkin Milky Way Meets Mega-monster Galaxy IC 1101

The Milky Way slices across the summer sky reached Cassiopeia and Perseus in the northeast down to Sagittiarius in the south as viewed from mid-northern latitudes. The galaxy is comprised of billions of stars, star clusters, gas clouds and planets. Credit: Bob King

We have the barest inkling of how truly vast the Milky Way galaxy is, but looking up on a dark summer night is enough to convince you it must be REALLY big. After all, this garland of hazy light speckled with stars touches both ends of the sky, north and south.

Astronomers have measured the galaxy’s diameter at 100,000 light years which means little until you appreciate that one light year equals 6 trillion miles, the distance a beam of light travels in one year. The fastest spacecraft ever built, the Helios probes, reached 157,000 mph (253,000 km/hr) as they zipped around the sun studying the solar wind from the mid-1970s to 1985. While that’s nine times faster than the International Space Station, it would still take 4,383 years to travel one light year at that phenomenal pace.

The Milky Way is a spiral galaxy with a prominent dense bar of stars across its core. The sun and planets are located with a spiral arm some 27,000 light years from the center. Illustration: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Even fleet light takes 100,000 years to cross from one side of the galaxy to the other. A light ray leaving Earth 100,000 years ago, when Neanderthals were the dominate human species in Europe, recently arrived there in our mobile-phone obsessed era. What will Earth look like 100,000 years from now?

Vast as the Milky Way is, it’s dwarfed by IC 1101, a faint galaxy residing in the center of the rich galaxy cluster Abell 2029 in the constellation Virgo. Located a billion light years from Earth, IC 1101 is the largest known galaxy with a diameter of 6 million light years or at least 60 times the size of the Milky Way.

Earth’s huge and tiny at the same time depending upon your perspective. Credit: Lsmpascal

You’ve probably all seen the illustration comparing the size of Earth to the sun. We sure do look tiny. Now multiply our one star by 200-400 billion – that’s the number of stars in the Milky Way – and consider that many of them likely harbor planets. Impressive place this Milky Way … until you park it alongside IC 1101 with its 100 trillion stars.

The Milky Way fares well in the neighborhood “Local Group” cluster of galaxies. It and Andromeda are the largest of its approximately 54 members. Credit: Andrew Colvin

Galaxies can be broken down into three basic types: spirals (like the Milky Way), ellipticals and irregulars. Spiral galaxies’ cores glow yellow from billions of older stars that formed in the galaxy’s youth that have since aged and evolved. Hot, new stars, which are generally bluer in color, coalesce from dust and gas within the spiral arms that wind around the central hub.

Ellipticals are spherical or flattened like a footballs and generally featureless. Most appear like foggy patches of amorphous star-haze. At a young age, they quickly converted their dust and gas into billions of stars that have since aged and yellowed like the ones in the Milky Way’s core. No spiral arms or fresh-faced hot stars here.

Giant ellipticals like IC 1101 usually start out small, beginning with the merger of a few modest galaxies within a cluster like Abell 2029. But if the process continues unchecked,   a monster is born. Over their lifetimes large ellipticals can rack up a lot of mass, and the bigger they get, the more gravitational pull they exercise over their environment, sucking in even more galaxies. Large elliptical galaxies are common features in large, rich galaxy clusters.

IC 1101, the largest known galaxy, dwarfs all the others including another large elliptical galaxy M87, also in Virgo, Andromeda and the Milky Way. Credit: NASA

If you could put IC 1101 in place of our Milky Way it would encompass a volume of space big enough to include our galaxy and its satellites the Large and Small Magellanic Clouds plus the neighboring Andromeda and Triangulum galaxies. That’s I what call supersized!

Every time we look at the sky, we can’t help but be taught a lesson in perspective. Earth’s an atom compared to the Milky Way, and the Milky Way’s a mouse at the feet of IC 1101. Our job is to find our place in this vastitude.

To assist you in your journey, a great place to start, besides the night sky of course, is Cary Huang’s wonderful Scale of the Universe 2.


13 Responses

    1. For Science

      Let’s see… Pluto is 2368 KM across, or 2,368,000 meters across. The area would be 5,607,424,000 KM^2 (Going in KM for simplicity). Converting light years to km, I found the diameter of IC1101 to be around 47,500,000,000,000,000,000 KM. The Area is around 2.25e+39 2,250,000,000,000,000,000,000,000,000,000,000,000,000 KM^2.
      We can find the amount of Plutos in 2D then by dividing IC1101s area by that of pluto, which is about 4.0236836e+29 or
      402,300,683,600,000,000,000,000,000,000. So you could fit 402 nonillion, 300 octillion, 683 septillion, 600 sextillion (*5,000,000 maybe if we are going in 3D, but it is hard to see the volume of a far away galaxy) Plutos in IC1101. I have too much time on my hands.

  1. Edward M. Boll

    I could hardly see Spica until I covered my hand over the Moon. This looked lie a closer conjunction than the pictures. I noticed something maybe worth noting. Both ISON and Siding Spring 2013 A1 come out of the Sun’s glare roughly about the same time, late August. Siding Spring remains low and will be poorly placed at least through the first half of 2014, out of view for most of that time.

    1. astrobob

      Hi Edward,
      I wonder if you had hazy skies or maybe you live far south of Duluth, where they would have been closer together. The diagrams were made for the northern U.S. It was easy to see it next to the moon from my home last night around 10 p.m.

  2. Hey Astrobob,
    Your article is awesome to read. I was recently searching about this galaxy in other sites. This article :- says some good points too. I think it would be great if you see this article and add some points accordingly.

    Thank You

  3. Timothy K. Ready

    When are you guys going to admit you’re all just making this shit up??? That first comment is ridiculous- “nonillion”, “sextillion”…where’s your proof of this???
    And if we’re IN the Milky Way…how is it we can SEE it from our planet??? And how do you “scientists” get pictures of the whole galaxy??? Sorry, try passing off your nonsense on somebody else…this is all pretend, like “quantum physics” that says you can walk thru walls…you’re full of shit…

    1. astrobob

      No, we can’t get out and see our galaxy from above the way you see galaxies in many photographs because we’re stuck inside of it in the mid-plane. We can however take a picture from the inside using dust-penetrating infrared light to show our galaxy as you would see it edge-on. Astronomers have also worked for decades using radio telescopes to map near and distant spiral arms. When you take what we can see from inside and combine it with data from radio astronomy, we can create a model of the Milky Way that shows us approximately what it looks like if you were to get outside and see it from above. You’ll notice that’s exactly what the Milky Way model attempts to show. It’s our best approximation.

    2. caralex

      Timothy, can’t you make your points (nonsensical as they are) without being vulgar? Do you think that vulgarity strengthens your argument? You’re sadly mistaken if you do. It just makes you look ignorant.

      Are you unable to look around you and see Earth, because you’re ON Earth? Think about how stupid that argument is.

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