![]() ![]() IPad 3, iPad 4, iPad Air, iPad iPad, iPad Mini 2, iPad Mini 3, iPad Mini 4, 9. IPhone 12 Pro Max, iPhone 13 Pro Max, iPhone 14 Plus: 1284x2778 IPhone Xs Max, iPhone 11 Pro Max: 1242x2688 IPhone X, iPhone Xs, iPhone 11 Pro: 1125x2436 Reflection Nebula - A nebula that does not emit light of its own but shines because starlight is scattered or reflected off the dust cloud. IPhone 6 plus, iPhone 6s plus, iPhone 7 plus, iPhone 8 plus: 1242x2208 IPhone 6, iPhone 6s, iPhone 7, iPhone 8: 750x1334 IPhone 5, iPhone 5s, iPhone 5c, iPhone SE: 640x1136 IPhone: iPhone 2G, iPhone 3G, iPhone 3GS: 320x480 A thousand light years will do me just fine.MacBook Pro 13.3" Retina, MacBook Air 13" Retina, MacBook Air 13.3"(2020, M1): 2560x1600 Dual monitor: For something like that, it’s always best to be sitting at a safe distance. Which is something you should be thankful for you don’t want to be too close to something like that…especially since, in a few million years or so, it’ll explode as a supernova. Only one star in a thousand is as massive, hot, and bright as it is. Mind you, that whole glowing gas cloud is something like five light year across-50 trillion kilometers (30 trillion miles)! But HD 34989 is a monster. It’s hard to believe all that is lit by a single star, but it is. This is very similar to what lights up the Orion Nebula and other famous (and gorgeous) objects. The edge of it is being lit by the star, making it look brighter. See that sharp ridge of red at the bottom left of the nebula, right where we start to see blue light? That’s probably the edge of a large, dense cloud of dust called a molecular cloud (those are common in that part of space). ![]() Interestingly, not all the dust in that cloud is scattering the star’s light. You can see why astronomers use these filters it helps distinguish what’s physically happening in the nebula. On Flickr I found a nice set of images showing how the reflected and emitted light can be combined to make a single image like Adam’s. Not always, but that’s clearly the case here in fact they have two different names: vdB38 for the reflection nebula and Sharpless 2-236 for the emission nebula. Many times where you see a blue reflection nebula you also see red emission gas as well. The star is blue, so it makes the dust look blue. When the light from the star hits it, that light gets scattered every which way, and some of it heads toward us. It’s strewn throughout the galaxy, especially where you see big gas clouds. It’s just the blue light of the star reflected! In this case, the culprit isn’t gas, it’s dust-thick clumps of complex molecules created when stars are born, and when they die. So where does the blue come from then? That one’s easier. In this case, the cloud is called an emission nebula. There is a special Hα filter astronomers use to specifically observe that light, which Adam used in this picture to enhance the glowing hydrogen. So in this case the gas is energized by the star, and responds by emitting that glorious red color. It’s very common in warm gas clouds where some bright star is nearby. This emission is called hydrogen-alpha, or H-alpha for short (or even Hα if you want to get all fancy and Greek). When an electron makes that drop, it emits a photon (a particle of light) in the red part of the spectrum. Every time it does that, it gives off a little bit of light.Īs it happens, one of those energy level jumps is very popular among the excited hydrogen atoms. Due to complicated quantum mechanic effects, the electron jumps down a series of discrete energy levels, a bit like a ball rolling down a staircase. If one meets up with it, they combine once again to form a neutral atom. But then the remaining atom (really just a proton) has a positive charge, and attracts any electron around it. When an atom of hydrogen gets zapped with UV, the electron gets blown off the atom. The gas cloud has a lot of hydrogen in it, which loves to absorb that UV light. In fact, it gives off a lot of ultraviolet light. The star HD 34989 is emitting light, and that light is very blue. One is if it reflects light from a nearby source (which is how we see the vast majority of objects around us), and the other is if it is intrinsically giving off, or emitting, light. ![]() There are two ways for an object to be visible. The gas and dust are obvious, too…but what’s the deal with those colors? Why is some of the gas red, and some blue? HD 34989 is pretty obvious it’s the intensely bright star in the middle. Adam took this picture with the 0.8 meter (32 inch) Schulman Telescope (RCOS) on Mt. ![]()
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