Unfortunately we’ll never get to visit them in person if Prostetnic Vogon Jeltz has anything to say about it:
We are about to jump into hyperspace for the journey to Barnard’s Star. On arrival we will stay in dock for a seventy-two-hour refit, and no one’s to leave the ship during that time. I repeat, all planet leave is canceled. I’ve just had an unhappy love affair, so I don’t see why anybody else should have a good time.
Just 6 light-years away, Barnard’s Star is a well-studied 10-billion-year-old M dwarf with a mass of 0.16 solar mass. Finding exoplanets around Barnard’s Star has been something of a white whale for astronomers for more than half a century; starting in the 1960s, researchers have claimed to have spotted various planets around Barnard’s Star, from distant Jupiter-mass companions to close-in super-Earths. Each of these claims has been refuted.
Now, the white whale appears to have been caught at last. Just last November, researchers reported the discovery of a planet orbiting Barnard’s Star with a period of 3.154 days. The data hinted at the presence of three other planets, but these candidates could not be confirmed. In a new research article published today, Ritvik Basant (University of Chicago) and collaborators leveraged years of data to confirm that Barnard’s Star hosts not just one, but four planets.
Good summary, but to everyone else reading this, it’s really worth it to read the article. It’s short and yet, frankly, fascinating. It discusses the methods used to identify the exoplanets and their orbital periods.
To think how hard it is to confirm these planets, for such a relatively close star. When we have already confirmed so much about objects at far greater distances.
Hard to comprehend these achievements from our individual perspectives. 👏
I wonder if Kepler or others would have found these planets had Barnard's Star been in the areas searched? I.e., very small planets in close orbits around a dim star is a very difficult target, period. This also means that the thousands of systems we now know about certainly have far more than the few bodies we've detected because we can only see the biggest ones well.
As someone who doesn’t know or understand any of this math/physics. Would you mind doing a super simple explanation of how the calculation works and why you chose certain factors?
Might be a dumb thing to ask but just curious and want to understand more.
D_nominal, D_min, and D_max represent the most likely, minimum, and maximum (well technically not maximum, just 3 standard deviations from most likely, of which 99.7% of trajectories will fall within) distance 2024 YR4 will pass from the center of the Moon (NOT the surface). They're taken from the linked NASA website. R_moon is the radius of the Moon.
L_impact is length of the impact corridor (the line where 2024 YR4 could impact the Moon). Since it doesn't pass through the center of the Moon, it's not simply 2*R_moon and so we need a simple formula to calculate it from R_moon and D_min.
P(x) is a probability density function; it's the black curve you can see. It shows, for a given trajectory along the line of possible trajectories, how likely 2024 YR4 is to follow that trajectory. It's shifted a bit from the center since the most likely trajectories are not exactly centered on the Moon. P_impact is the area of P(x) that falls within +/- L_impact, AKA the probability that the trajectory will intersect the Moon, AKA the impact probability.
The rest is just some graphing stuff that doesn't matter to the calculation.
AKA the probability that the trajectory will intersect the Moon, AKA the impact probability.
(Disclaimer, I know close to nothing about these) Am I pedantic about a useless detail or does it significantly change the probability if we consider that an object may still impact the moon after “missing it” if it comes close enough to be captured and come back after a semi orbit? Or do the relative speeds makes this extremely unlikely?
This is a great question. It’s like asking when a rock is too small to be a planet. I suspect there were be a definition eventually that mirrors the planetary definition – something like “spherical(ish) and clears its orbit”. The issue is that Mars would lose its two moons under that definition.
So we might end up with something like “moons” vs “natural satellites” and Mars will just have to suck it up.
The Earth’s moon is believed to have formed from a similar process, the researchers explained in a written statement, but it was more like a slap in the face rather than a kiss.
See above caveat from the article that makes the title a bit misleading.
A kiss-and-capture scenario works for Pluto-Charon because those two planets are so compositionally different.
The Earth and Moon are so compositionally similar, that in an impact scenario they would have needed to exchange a lot of material. It would need to be a catastrophic impact, not just a kissing/glancing blow. More of an explosive round that penetrates and detonates its energy. Boom and reform, not just a slap to the face.
Do NOT buy a $200 telescope new. You’re going to overpay to get a piece of kit that’s okay at best and unpleasant to use at worst (possibly due to uncomfortable eyepieces, difficulty in actually using the scope with bad alt/az controls, bad ergonomics with the stand, etc).
If you want a cheap scope just to find out if you’ll like amateur astronomy: Go hit some garage sales or a resell app or Craigslist or something, but I particularly recommend garage sales. There’s plenty of these cheap ‘hobby killer’ telescopes that can be had for a fraction of their retail price this way, and the resell value is a little more reflective of what they’re actually worth.
Alternatively: drop about 1/4 of that on some good binoculars. You can absolutely stargaze with binoculars, I actually always bring some when I do public outreach. I’m very fond of 7x50s, because the low magnification (the 7) works really great on open clusters and makes them easier to steer, while also not being so heavy that they wear out your arms after ten minutes. The 50 describes the aperture size, which means that your binoculars will have plenty of light- gathering capacity. The bigger the apertures, the more light they’ll collect, but the heavier and harder to use they’ll be. Plus, their magnification won’t be too far beneath the maximum magnification of a generic retail telescope.
If you want a great starter scope: I’d suggest that you save your money, don’t burn your budget on a crappy retail refractor. I’d also suggest doing one of the two above things to decide if you even like astronomy enough to spend the money on a good scope. If you do like it, and you do want a good starter scope, it’s hard to go wrong with a 6" dobsonian. They’re relatively cheap for what they are, very portable and manageable, and there’s a LOT you can see with them, even in the city, but especially in dark skies. Also, you could probably find some good used ones in your area for a bargain; there’s lots of folks who splurge on telescopes and fall out of love with them, and then just have it sitting in the corner of the garage for years and years. Like I said, garage sales are really great for this.
Btw, don’t get aperture fever and splurge on a double-digit aperture. I did that, but I specifically did it for outreach purposes; if I was getting it strictly for my own use, I’d have a $1500 oversized dust collector because it can be a real PITA to move outside.
I never even thought about garage sales! Is there a way you can test to see if they’re damaged or defective in the middle of the day? I’d hate to purchase a broken one without even knowing it.
Tl;Dr getting focus before you leave isn’t SUPER important. It can be kinda tricky to figure out for newcomers, and you’re better off using your time to assess the action and components of the scope.
Yeah, so, you’re going to want to spend some time on YouTube U learning about how to focus a telescope. It could be trickier with a dobsonian/newtonian because you may need to collimate it (though the smaller the telescope is, the less important that becomes) to see clearly, and someone at a garage sale may or may not be willing to do it for you / trust you to do it. Generally speaking, though, if all the moving parts move like you expect them to and don’t move like you don’t expect them to, the lens or mirrors aren’t obviously damaged or scratched, the eyepieces aren’t obviously damaged or scratched (eyepieces are MUCH more sensitive to any kind of damage than mirrors or lenses in terms of user experience), then you’ve got a winner. It’s hard to think of a situation where a telescope’s parts would be in working order and good condition but somehow be broken in a way that prevents it from achieving focus.
For assessing movement: with a dobsonian in particular, but really any mount, you’ll want it to be very easy (ALMOST but not quite frustratingly easy) to move the telescope so that you can track targets across the sky easily. The telescope, however, shouldn’t move on its own without some force acting on it (i.e. touch, wind, etc). If it’s moving under gravity, then either the balance is off (very possible with a dob, and usually easy to fix too), the friction is off (also an easy fix with a dob), or the mount could be bad if it uses some other kind of altitude-azimuth (left-right-up-down) mount that uses clamps and locking knobs and such. Also, make sure you try adjusting the focuser tube. They stick out and tend to get whacked, and if your focuser tube is busted, you’re SOL. Just check to see that it moves when it should and not when it shouldn’t, and that it goes all the way in and out without falling out; if it doesn’t, check for some little thumbscrews on the focuser. Sometimes, when those are tightened down, they’ll keep the focuser from moving, or let it move way too easy if they’re too loose. If those thumbscrews aren’t the problem, then the focuser is busted and you should give it a pass.
I also highly recommend checking the finder scope- that’s the little buddy telescope that’s attached to the telescope that’s there to do business. They stick out a bit and have a habit of getting damaged. It’s not a huge deal if it’s broken, they can be easily replaced, but you’re going to want to replace it before you head out or you’re going to have a bad time. Lots of people love Telrad finders, I’m an absolute nut for RACIs; beware the little straight-through scopes, though, as they’ll murder your neck when you have to look at something high up.
If you really want to try and look at something (not a bad idea, per se, just not the most effective use of your time. I’m assuming neither you nor the seller will immediately know how to achieve focus with the scope), try to pick something both big and very, very far off. If the moon’s up, try looking at that. If not, try to pick the furthest, biggest thing you can see (big makes it easy, but if it’s too close, you simply will not be able to get focus on it, period) and try to sight it in.
This deserves its own post because I nearly forgot but it’s kinda important:
If you end up buying a reflector telescope from a garage sale, DO NOT CLEAN THE MIRRORS. Unless you can’t see your reflection in them at all, just don’t touch them. You’ll be shocked at how little the dust actually impacts your view, but these mirrors are super crazy easy to permanently mess up. If you must clean them, DO NOT use a rag, DO NOT use compressed air! Use a gentle stream of distilled water to rinse it clean. The big danger here is that you could end up dragging sharp/hard debris across the mirror and cutting some serious gouges into it. This is also true of the eyepieces. Don’t use re-usable rags to clean them. I use lintless cotton eyeglass patches to clean my pieces after fogging them up with my breath (that’s cheap and readily accessible distilled water) once I’m satisfied that they’re free of any large debris. I wipe in one direction, flip it, wipe in another direction, and dispose of it. That’s it. The eyepieces being a little dirty will mess up your view, but a dirty mirror probably won’t. Only clean it if you’re 300% convinced that you must.
Also good advice: try using the telescope at least twice before you go to the event. The moon is probably the easiest, brightest target, and it’s a good place to start with making sure your focus is close to perfect. Once you’ve got the moon, move on to a few slightly more challenging but still easy targets that you should be able to see, even in an urban area, to make sure you understand how to use the scope and put it through some actual use. A pretty easy target would be the first star out from the cup on the handle of the big dipper. Tell me what you see when you find it in the scope. Jupiter is also a pretty easy, rewarding target. The sword of Orion is another bright, easy one. Lastly, Venus is a really easy target and has a little surprise for you when you find it. But two uses is enough to get familiar with your equipment, get familiar with its use, and identify any problems before you actually get out there.
Thanks a lot for all your advice! I looked around Craigslist and ended up finding an astronomy enthusiast who was upgrading his gear and gave me a great deal. I purchased a Sky Watcher Heritage 130 Tabletop Dobsonian, SVBONY SV225 Alt-Azimuth Mount, and a SLIK PRO 700 DX AMT tripod for about $208. The MSRP with tax is easily triple that! The equipment was in great in shape and I could easily see some of the brighter stars in a Bortle 8/9 sky relatively easily. I plan to purchase a couple of light filtering eyepieces for seeing the sun and moon to complete the setup.
Hey, that’s awesome! Great job! It’s going to be real easy to drop a LOT of cash on eyepieces. Don’t. Start on the cheaper side and only move up if you find that the eyepieces are limiting your viewing experience. A lot of people really like the 8-24 mm click-stop zoom pieces for starter eyepieces, though I don’t have any experience with them. If you really want to splurge, buy a wide field of view piece. The full moon will be a deadly laser but doable without a filter. The sun will literally set your eyepiece on fire. I’ve seen it happen. An eyepiece filter will not be enough to protect you or your equipment from the sun. There are filters that will fit over the aperture (the end of the tube) that are basically the same material as solar eclipse glasses, and that’s what you need. They aren’t expensive, last I looked, though, again, I have no experience with them. For a list of possible targets to get some practice, see astroleague’s urban observing program here: www.astroleague.org/urban-observing-program/Note that there’s a separate list of multi-star systems you should be able to split (see at least two distinct stars) in a scope of your size. I’d also recommend using Stellarium; it’s a free app that’s actually free, and it’s absolutely dead useful for learning the night sky and planning/aiding viewing sessions. I use it to help me plan my outreach outings, and I really can’t recommend it enough. Best of luck, I’m really happy for you, and please let me know how it goes!
+1 on binos. They’ve kept me happy because they fit in a backpack or carry-on luggage. I’m deep in light pollution, so viewing is best done with some travel. They have less magnification, but they’re as bright as a much more expensive telescope and there’s a certain value to having two eyes on the night sky.
10x50 is where I landed. Probably the same weight as your 7x50. While yes, the 50(mm) describes the outer objective lens, the key thing is really the lens on the eye side. Divide the aperture by the mag and you find that exit pupil size. 50/10=5mm, which is about the size of a dilated adult eyeball pupil - and they get smaller as you age. I’m guessing you have a Celestron or similar astro bino which has some advantages for this hobby. I am surprised at the ~$40 price tag, so I no longer want to recommend against it. Where I WAS going was that 7x35s would likely give a similar image from a reputable manufacturer while saving a little weight and being more likely to be found at a garage sale. But who could say no to $40 new 7x50s? As long as OP avoids those 20x50 boating binos or 10x25 hunting binos, they’ll be in good shape. My 10x50s are closer to OP’s budget because I opted for Nikon Action Extremes to survive my beach spot, hikes, travel, drops, and any other mishaps alike. Things go bump in the night so rubber coating and waterproofing was worth it to me
I use 7x35s for outreach and they work pretty well. I got my kids the Celestron 10x50s and can’t recommend them enough. They’re really, really great. Not too heavy or bulky, even for kids, but still very capable of enhancing your stargazing experience. They can juuuust about split a Galilean moon, IME; Jupiter will look a little odd, but I haven’t been able to distinctly identify a moon with them.
By split a gallilean moon, do you just mean see up to 4 moons separate from Jupiter? I’m pretty sure I can distinctly see them, at least with elbows on a railing or on some mount. I guess I’ll have to look tonight if it’s clear. I kinda only remember catching 3 at a time and not investigating further. I do have 20/15 vision so I guess that plays a role. Good point to remind me not everyone has my hawk eyes. I don’t catch much color though. Usually too small and washed out. It’ll have slight pink bands at best. I haven’t been able to note a crescent shape for venus, either. But I figure even cheap scopes can show my planets, so it hasn’t been my focus
Yeah, that’s what I mean. I’m impressed! For me, Jupiter looked kinda smeary, like looking at it with an astigmatism, only it wasn’t an astigmatism, it was the moons. As for Venus, I guess you might just need higher magnification to cut through the glare and resolve the crescent. The minimum power I use in my dob is 50x and you can clearly see the crescent at that power.
Alright, seeing the moons was harder than I remember with 10x50 Nikon AE. Handheld, about 80deg up. For a few moments, I could pick them out, but the shakes got too intense to see them again reliably. That’s with decent knowledge of what to expect. My memory is probably based on the one time I actually used my homebuilt parallelogram mount. Or maybe when jupiter was 30deg up and my elbows were on a railing
Hey, it’s cool that you followed up with this! It would make sense that the shaking is too intense for the fine details, especially at that high angle. I feel like I’ve heard of people using image-stabilized binos for stargazing, maybe that could make a difference?
Looking at the prices, my cheap ass would sacrifice some portability and opt for a tripod and a lightly fabricated aluminum or oak stick (read: drill 3 holes) to make a 24-36" offset mounting plank and carry a 5lb counterweight
astronomy
Gorące
Magazyn ze zdalnego serwera może być niekompletny. Zobacz więcej na oryginalnej instancji.