• Luke

Whats up this summer!

Updated: Jul 16

Here's a list of what you will see on an AstroTour this summer! M44 - Beehive Cluster [in cancer] (back up open clusters: M39[Cyg], M11[Sco], M6[sco], M21[Sag], Double Cluster [Per])

M44 the "beehive" cluster

  • Open cluster

  • Can be seen as a mist, cloud, or fog with the naked eye. Kinda like a little drip of the milky way that strayed.

  • “Town of stars, just down the road” aka: Thousands of stars, hundreds of light years away (actual distance 520 to 610 ly, and about 1,000 stars).

  • like little towns of stars just down the road like Lyons, Jamestown, or Nederland. Hundreds of light years sounds far and it is a mind boggling large distance but compared to the globular clusters and galaxies (thousands and millions of light years away respectfully) we look at, it is just down the road.

  • What does it look like to you? I hear some say an arrow head, some say, bees, butterflies, etc. some just say “stars”

  • Try to count/estimate how many stars you see it should be at least ~70 so this might take a while

  • Open Clusters are like teenage stars. They were likely all fourmed closer together, in the same star forming nebula (or more simply “stellar nursery”), and are now spreading out leaving the nursery and going their own ways in our galaxy

  • Cloud of stars in our galaxy ~39 light years wide with a core that’s about 11 ly wide

  • Total mass is about 550 times that of our sun

  • Age of the cluster is about 650 million years old

  • I think of this like young or *teenage* stars. Stars get to be billions of years old, our sun is 4.6 billion years old

  • One of the first objects Galileo studied in a telescope. First called “little mist” by a greek poet in 260 BC

  • The main thing to see in the constellation Cancer

  • Seen as a manger and the two stars next to it seen as donkeys eating from the manger by the Greeks and Romans

  • In China it was seen as a ghost riding a chariot and is one of the 28 chinese zodiac signs (lunar mansions)

  • Origin of calling it the “beehive” is unknown.

Location of M44 the Beehive Cluster

M13 - Hercules Cluster [in Hercules] (back up globular clusters: M4 [Sco], M5 [Ser], M22 [Sag], M3 [CVen], M92 [Her])

M13 - Hercules Cluster

  • Globular cluster

  • “city of stars” Thousands of light years away, Millions of stars (actual distance 23 thousand ly away, about a million stars) like far away a mega city of stars like NY, LA, Madrid, Tokyo. thousands of light years away is far compared to the open clusters we look at but it’s still in our galaxy and really close compared to the galaxies we look at.

  • We’re seeing how it looked 23 thousand years ago because it’s 23 thousand light years away but little has probably changed as these clusters are ancient.

  • M13 is twice the age of our solar system at 11.6 billion years old

  • M13 is about 84 light years across and if our solar system was in it we would have about 500 times more stars in our sky as it’s so dense with stars

  • Can’t count all the stars, many stars can be seen on the edge of it but as you get closer to the center core it becomes a fuzzy glob of star light from millions of stars shining together.

  • What does it look like to you? I usually get spider webs, or shards of glass. Sometimes I hear spilled salt or sugar. My favorite is a girl scout who said it looked like a dandelion seed ball just before you blow it out. My least favorite is a nurse who told me it looks like COVID in a microscope.

  • On really dark moonless nights you can just barely make it out with the naked eye as a faint fuzzy star if you have really good eyes

  • Easily found in binoculars, first look for the “keystone” of hercules (Vega in the summer triangle points at the key stone) Then it’s about halfway in between the western most two stars of the keystone (see chart on other side).

  • Discovered in 1715

  • Brightest and richest of all of the globular clusters in the northern hemisphere. (omega centauri, and 47 Tuc are only two that are brighter but they can only be seen in the southern hemisphere)

  • We usually show at least two globular clusters to show how different the globular clusters can look. I think M13 looks more like an american city (like dallas/ft.worth) with sprawling suburbs, where M92, and some of the others, look more like a european city with a dense urban core (like Madrid or Tokyo).

  • In 1974 we sent a high powered radio signal called the arecibo message (named after the now defunct arecibo observatory that sent it) to M13 potentially telling any life in M13 about life on earth. It will still take over 23 thousand years for the message to reach M13 and another 23 thousand years for a response (if any) to come back

  • Globular cluster’s origin is a mystery, usually said to be old cores of galaxies that our galaxy has run into and consumed/captured. This has been called into question as there’s a nebula (the tarantula nebula) in a satellite galaxy of ours (the large magellanic cloud, unfortunately only seen in the southern hemisphere) that seems to be forming a globular cluster. The mystery being that all globular clusters we see (even in other galaxies) are made up of super old stars, except for one; right on our doorstep we see what looks like it’s one being born. So if you can think of a story for why that would be, I would love to hear it and I would love even more to be cited on your paper when you write it ;)

Location of M13 - Hercules Cluster

M81 - Bode’s “Nebula” {galaxy} [in the big dipper (UMa)] (back up galaxies: M82 (whirlpool) [UMa], M51 (sunflower) [CVn], M104 [vir], M64 [com], M63 [CVn], M87 [vir], M86 [vir], M66 [leo]

M81 - Bode’s “Nebula”

  • Galaxy

  • Billions of stars, Millions of years away

  • Looks like a faint fuzzy thing, can no longer see individual stars (too many stars too far away) but only see millions of stars shining together in a luminous cloud.

  • 12 million lightyears away, the light (photons) you’re seeing left that galaxy 12 million years ago and has been traveling all the way through space for 12 million years to land in your telescope and interact with your retina so you are having a physical interaction with a galaxy 12 million light years away… not bad for a “faint fuzzy” thing

  • 70,000 light years across

  • The furthest away we will look in the telescopes much farther than the globular or open clusters

  • Everything we look at tonight exists a multitude of times in this other galaxy. This galaxy has about 250 billion stars, each of those stars just like our sun likely has many planets, and many of those planets have multiple moons, it has thousands of nebulae, thousands of open clusters, and hundreds of globular clusters.

  • It’s called bode’s “nebula” because before the 1920s we didn’t even know other galaxies were out there and everything astronomers saw that were faint and fuzzy in a telescope were called “nebula”. It wasn’t until Edwin Hubble using the biggest telescope at the time looked at this galaxy and about a dozen others and realized that they were other galaxies. It wasn’t until the 1930s that other galaxies became widely accepted as astronomers had thought our galaxy to be the entire universe at the time, and Hubble was saying our galaxy was just one of many. Now NASA has cataloged over two trillion galaxies (that’s just what they’ve counted, we know there’s more), so less than 100 years ago astronomers thought the universe was half a trillionth of what we know it to be today. Makes you wonder what the next 100 years holds for us

  • There is a black hole in the middle of M81 that is 70 million times the mass of our sun

  • If there’s extra time we show M82 as well it’s right next to it and shows how different the galaxies can look if you’re looking edge on (M82) or more of a top view of the full disk (M81)

  • M81 and M82 collided a few hundred million years ago causing M82 to be deformed.

  • M81 is 150,000 light years away from M82 right now

  • M81 and M82 are still interacting gravitationally this has pulled some gasses from M81 to M82 letting M82 form more stars

  • In zoomed out binoculars you can get M82 and M81 in the same field of view.

  • Can’t be seen with the unaided eye but easily seen in decent binoculars

  • Can be found by using the diagonal stars of the vessel of the big dipper as a pointer (see chart)

  • Discovered in 1774

  • It’s slightly bigger than our own galaxy.

Finding M81 - Bode’s “Nebula” with the big dipper

M57 - Ring Nebula [in Lyra] (back up planetary nebula: M27 [Vul], NGC 7293 (helux) [Aqr], NGC 7009 (saturn) [Aqr], NGC 6543 (cats eye) [Dra], NGC 2392 (eskmo) [Gem], NGC 3242 (ghost of jup) [Hyd])

M57 - Ring Nebula

  • The “ring nebula” is a planetary nebula

  • Looks like a little cheero ring or little poof ball

  • It’s actually about 1,000 times the size of our entire solar system

  • Sometimes you can see a little white dwarf star left behind in the middle this “dwarf” star is actually about the size of earth

  • Planetary nebulae are called “planetary” by mistake, early astronomers thought the little disk looked like a planet in a telescope.

  • The ring nebula is only seen in telescopes (you won’t see it with just your eye and won’t see it even in fairly good binoculars)

  • You might be able to notice the ring isn’t perfectly round but slightly elliptical in the telescope

  • It’s roughly 2,000 light years away but it’s hard to really tell how far it is

  • It’s about 7,000 years old

  • Usually seen as white but some eyes see it as greenish

  • “A ghost of a star”, planetary nebulae are stellar ghosts. They are old exploded star remnants

  • It was a sun like star that blew away the outer envelope leaving behind the earth size white dwarf

  • Stars are a very complex topic in astro physics, there’s a whole separate part of physics called heliophysics that’s the study of stars. You can get a PHD in heliophysics and still not know everything about stars. So this is an oversimplification and don’t worry if you don’t get it:

  • Stars are really really big

  • Our star the sun is 112 times the diameter of earth, if you square that to get the volume it’s over 1 million times the volume of earth

  • The gravity on the sun is also about 1 million times that on earth

  • If you were on the sun you would weigh 1 million times what you do now and collapse under your own weight

  • Because of the immense gravity everything on the star is collapsing to the center pushing really really hard on the center. It pushes so hard that the nucleus of the atoms in the center core of the star are being pushed to touch each other this is called “fusion”

  • Fusion causes a huge explosion (the only time we’ve ever done fusion on earth was the hydrogen bomb) this explosion starts pushing aginst the immence gravity of the sun and balances the star out creating the consistent light we’re used to from our sun.

  • This balance lasts billions of years but eventually all of the hydrogen in the star is fused up. Hydrogen is the easiest to fuse (that’s why we did it in the ‘hydrogen’ bomb) once it’s gone the gravity starts winning and pushing harder on the core.

  • This increase of gravitational pressure pushes bigger and bigger elements together in fusion at the core (until Iron which will not fuse). Fusing these bigger and bigger elements means the explosion in the core of the star can go bigger and bigger, eventually it blows apart the star, pushing all the stuff that made up the star’s outer layer away in all directions in a ball of gas, leaving behind the core as an earth sized white dwarf star in the center.

  • That is what you’re seeing in the planetary nebula an old exploded star (if the star was bigger it could have formed a black hole… but that’s probably too deep of a theoretical physics conversation than you want to read right now)

location of M57 - Ring Nebula

Antares - Fake mars (back up any bright stars low on the horizon : Archturus, Vega)

size of Antares

  • Red giant star in Scorpio

  • The name Antares is Arabic and means mars’s rival

  • Both Antares and mars are bright red and both are on “the ecliptic” (the only part of our sky you can see planets) causing it to be mistaken for mars often.

  • The rivalry comes from Mars only being brighter than Antares one out of three years.

  • If we shrunk down our solar system so that the earth was 1mm big (about the size of a grain of sand), the sun at this scale would be 112mm (about the size of a grapefruit) and 10 meters (about 10 yards) away from our 1mm earth. At this scale Mars would be about a .7mm grain of sand and would be about 17 meters (~17 yards) from our 112mm sun.

  • Because Mars orbits the sun from further away than the Earth it takes Mars about 2 years to go around the sun (it of course takes the earth only one year to go around the sun). So that means once every three years we catch up with mars and pass it on the inside lane. So one year out of three we are on the same side of the sun as mars.

  • So going back to our scale one year out of three we are (17m-10m=) 7 meters (~7 yards) away from Mars, but two out of three years we are on the opposite side of the sun from mars (17m+10m=) 27 meters (~27 yards) away from Mars.

  • Antares being a far away star doesn't change brightness but getting closer and further from mars means mars brightness fluctuates a lot.

  • When we are on the same side of the sun as Mars, Mars is brighter than Antares but when we are on the opposite side of the sun from mars Antares wins the rivalry.

  • Antares is huge!!!

  • If the sun was replaced with Antares the earth’s orbit would be well inside the star, even mars would be in Antares if we swapped it for the sun as the width of antares is a bit bigger than mars’s orbit.

  • Antares is actually the biggest physical object you can see with the unaided eye.

  • If the sun was the size of a grape antares would be the size of a small car

  • Antares is the heart of the scorpion scorpio. You can see the red beating heart of antares on the horizon, above it and slightly to the right you can see a line of three stars that represents the head and two claws of the scorpion. Later in the summer you will see the tail and stinger rise above the horizon.

  • Scorpio is actually Orion’s rival. The Greek story is Scorpio killed Orion so when they put them in the sky they put Orion and Scorpio on opposite sides of the heavens. Because they are on opposite sides you can never see Orion and Scorpio together in the sky. It’s kinda like they have a restraining order.

  • Antares appears to twinkle or beat because of the atmosphere. If you imagine the air above us like a blanket, if you look directly up you’re just looking through the thinnest part of the blanket but as you look towards the horizon you’re looking through the length of the blanket. Because Antares is lower on our horizon you’re seeing it through more atmosphere which makes it twinkle more. Kind of like how when you watch the sunset over the ocean you can sometimes look at the sun’s last glint of light because the light is going thru so much of the ea