efaardvark

I just heard the same news. Losing Hubble and lost Kepler =/ we need to fund our space programs!

Probably going to lose DAWN here pretty soon too.  They're almost out of attitude-control fuel.

But TESS is already up.  TESS was originally planned as a follow-on to Kepler, but since Kepler lasted so long TESS has already launched and started sending us data.  (LOTS of data!  Its highest data rate is 125Mbits/sec, the highest data rate NASA has used to date for any of its probes.  The first downlink the spacecraft dumped over 50GB on us here in the DSN in just over an hour!)

After TESS there's already the James Webb Space Telescope being worked on.  They haven't launched yet though.  There will also be a lot of competition for viewing time on JWST since it isn't only a planet-finder.

Interesting, though I wish he provided a legend to read this stuff. He only provides 5 categories, but there are more than 5 colors it seems.

The text just above the table defines how the terms are applied.  The problem is that it is REALLY hard to even see these things, never mind determine their size.  There is so little light that even Hubble has trouble seeing them.  Basically you have to be looking at a star and notice that it disappears for a while.  That tells you that /something/ was there, and gives you a lower limit on the size.  (If you know approximately how far away it is then that gives you a read on the speed that it is travelling in orbit around the sun.  Based on that speed and the duration of the occultation you can determine that it has to be a certain size or larger.)  To be a "dwarf" planet, it has to be round.  Unfortunately, the composition determines how big a body can be before it becomes round.  How do you determine the composition of a particular body when you can't go there and can't even SEE it properly?  How do you know the size when the occultation time might be through the thickest part of an irregular object or might barely nick the edge of a larger round body?  Some of these things, like Haumea (spins so fast it is oblong, has two moons and a ring orbiting it), are really strange and hard to get a handle on.

You can figure things based on what you know, and you can put limits on what might be, what can't be, etc., but the error bars are pretty large.

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How many dwarf planets are there? Ceres is the only asteroid that is known to be round. After that it gets complicated. All of the rest of the new dwarf planets are in the distant region of the Kuiper belt, where we can't actually see them well enough to know for sure if they are round or not.

While we can't see most of the objects in the Kuiper belt well enough to determine whether they are round or not, we can estimate how big an object has to be before it becomes round and therefore how many objects in the Kuiper belt are likely round. In the asteroid belt Ceres, with a diameter of 900 km, is the only object large enough to be round, so somewhere around 900 km is a good cutoff for rocky bodies like asteroids. Most Kuiper belt objects have a lot of ice in their interiors, though. Ice is not as hard as rock, so it less easily withstands the force of gravity, and it takes less force to make an ice ball round. The best estimate for how big an icy body needs to be to become round comes from looking at icy satellites of the giant planets. The smallest body that is generally round is Saturn's satellite Mimas, which has a diameter of about 400 km. Several satellites which have diameters around 200 km are not round. So somewhere between 200 and 400 km an icy body becomes round. Objects with more ice will become round at smaller sizes while those with less rock might be bigger. We will take 400 km as a reasonable lower limit and assume that anything larger than 400 km in the Kuiper belt is round, and thus a dwarf planet.

How many objects do we know in the Kuiper belt that are 400 km or larger? That question is harder to answer, because we don't actually know how big most of the objects in the Kuiper belt are. While we can see how bright there are, we don't know if they are bright because they are larger or are highly reflective. In the past, we had to just throw our hands up in the air and say we don't know enough to even make reasonable guesses. But in the past few years, systematic measurements of the sizes of objects from the Spitzer Space Telescope and now the Herschel Space Telescope have taught us enought that we can make some reasonable estimates of how reflective objects are. (It's complicated: read the details here ) These reasonable estimates, combined with all available actually measurements, give us the list of the largest Kuiper belt objects, sorted by diameter, below. Carefully note the lack of any error bars. Every single measurement or estimate below is uncertain to some extent or another. I don't include the individual uncertainties in the table, but instead use the ensemble uncertainties to inform classification below. In other words: take the sizes of specific objects with bigger or smaller grains of salt.

 

Yeah, BT is a Good Thing.  For cellphones, well, I'm one of the 0.01% of the population that will actually turn off their cell connection when driving.  What calling I do is usually just 30-second "I'll be late" type notices when stuck in traffic.  Though I don't use it much, for those times hands-free calling is wonderful.  I also had a bluetooth gadget for wirelessly connecting my phone to my old car's "aux" audio input for spotify because I literally wore out my last phone's audio jack plugging/unplugging for the commute.  (I don't buy new phones very often either.)  I made sure this car had both hands-free phone and BT audio input built-in.

Most of the time, the apps stink, so it is a bad idea in that respect, but I still think they could be neat, especially if it could make the car invisible.

Nice looking car though.

I wasn't impressed with the apps I saw either.  The apps I want/need are already on my phone for the most part, and I don't need the distraction of dealing with any of the ones in my car while I'm driving.  The only apps I use with any regularity while actually driving are waze and spotify anyway.  I'll probably use the built-in GPS instead of waze because the car's display is bigger.  It would have been nice to have spotify built-in too, but with the BT connection that's not a big deal.  The car does have Sirius XM and Pandora.  XM I'll probably use for the 3 month trial and not miss it afterwards.  I have yet to try Pandora, even though I have a subscription.  That might be good enough to replace spotify when I'm in the car.  Other than that the rest is uninteresting at best, and distracting at worst.

Invisibility would be cool.  Dangerous, but cool. 

11yo car + frame damage = totaled.  Guess I'm going car shopping this weekend.   

Our last dog never really got the hang of swimming either.  She liked getting wet, and she would do a sort of log-ride splash thing where she'd run full-tilt into the water and splash everything/everyone nearby, but she didn't like paddling around at all.  If her feet couldn't touch the bottom she'd freak and try to get out of the water.

This is what a chiweenie looks like:

8 weeks old so still a bit of growing to do, but not going to get too much bigger.

Oh my....that is cute! 

yep im in to bigger dogs too , generally shepherd X's and the latest one (getting real old) thinks she's a lap dog the size of yours too , spends more time in side than me when im home

@Roxeg He is talking about a gaming PC.

A game box in this case is a computer to (mostly) play games.  On "his" old computer he mostly played minecraft, WoW, and Civilization.  Occasionally he'd get on his steam account and download something else to play for a while, but those are/were his main go-to games.  Something that could run those reasonably well, plus do stuff like email, web, etc.   His old system was an i3 with 4G ram and a Radeon RX460 w/2GB.

That makes a lot of sense. Don't know how I didn't think of it first.

Go on that marvelous journey with Vash the Stampede!

Not good to hear about that stuff, but I am glad you guys are not screaming “Oh my gosh, we’re burning alive!”

Nice share. The video was pretty interesting, but I feel like the guy could have made it longer. I so wanted to see an anti-tank round being used against an asteroid, because of what was said at the end.

If  the drones work as expected there will be video from the impact.  はやぶさ２ is an interesting mission.  Kind of Deep Impact, Rosetta, and Dawn all rolled into one, but on a budget.  It is a cool mission.

Sounds confusing, right.

Sorry to hear that, it's never easy (T_T)

If I knew where that was in the first place... enjoy!

This is the Jet Propulsion Laboratory's open house in Pasadena, California that we do every year.  It is a local thing for the most part, though we do get a few people coming in from out of state as well.  It is extremely popular, especially with the kids, so crowd control is an issue.  A few years ago attendance got up to over 40,000 for the weekend.  It was hot that year too, with temperatures over 100F.  We had to start issuing tickets to the event to limit the number of visitors as a safety measure.  (Tickets are free, but limited in number.)

What was celebrated?

its actually Saturday arvo here and TF I'm not working today

its a little after 4pm tue here ive been home a little over half n hr

after only a 9hr shift today