Comments on: MESSENGER’s family portrait

By: astrolabe_cat

astrolabe_cat — Wed, 23 Feb 2011 12:56:34 +0000

Damn it. That video has me sobbing.

By: Nigel Depledge

Nigel Depledge — Tue, 22 Feb 2011 15:26:38 +0000

Re: Pluto’s status.

I’m firmly convinced that the IAU (being the international body representing professional astronomers) should be free to define “planet” any way they see fit.

I do a lot of work in protein science, and if some laypeople came along and tried to tell my profession’s representative body how to define “protein”, I’d be pretty miffed.

By: Nigel Depledge

Nigel Depledge — Tue, 22 Feb 2011 15:24:02 +0000

The Messenger pic is very cool, but I’m sure I’ve seen a very nice pic of Earth and Moon taken by a recent space probe that gave a really nice feel for our home planetary system.

Thinks . . . maybe it was Messenger on a fly-by during its journey to lose enough orbital velocity to get to Mercury?

By: Nigel Depledge

Nigel Depledge — Tue, 22 Feb 2011 15:19:04 +0000

Ian S (44) said:

what is so special about Pluto?

Erm … it’s been mistaken for a planet for the last 80 years?

By: DigitalAxis

DigitalAxis — Tue, 22 Feb 2011 15:00:10 +0000

@41 MTU: on the other hand, there are a lot of astronomers who have NEVER considered Pluto to be a real planet. I’m one of them (never mind that I wasn’t alive until after Charon was discovered, which sealed the deal for many)

Obviously, if you swapped Ganymede and Mercury, Mercury would become a Moon; if you swapped Pluto and Mercury, it’d be Dwarf Planet (albeit a MUCH larger one in size and mass… context DOES matter. 2M1207b is currently considered (as far as I know) a planet, even though 2M1207A is a brown dwarf. Put 2M1207A in a solar system and it’s (just) conceivable we’d call it a planet and 2M1207b a moon.

By: Nigel Depledge

Nigel Depledge — Tue, 22 Feb 2011 12:49:01 +0000

Ed D (15) said:

A friend gave me an astronomy book from the 1890s and the author talked about looking up at the night sky from Venus and being able to see the Earth and Moon as naked eye objects. I have always loved that image; it’s nice to see an example of it in reality

This made me chuckle. We now know that you’d have to wait an awfully long time to get a clear sky on Venus!

By: Neil Haggath

Neil Haggath — Mon, 21 Feb 2011 13:04:13 +0000

#27 HP, #33 Pete Jackson:
Earth and the Moon are not a double planet, in the sense that Pluto and Charon are.
Pluto and Charon are regarded as a double planet ( or double dwarf planet now! ), instead of a planet and satellite, for a very good reason; they are the only pair of planetary bodies in the Solar System, for which the barycentre lies in empty space between them.
For all other planet-satellite pairs, the barycentre lies inside the primary body – including the Earth and Moon. Earth has 81 times the mass of the Moon, and their separation is only 60 Earth radii, so the barycentre lies inside the Earth – significantly displaced from its centre, but still inside it.

By: IanS

IanS — Mon, 21 Feb 2011 09:13:26 +0000

@41 MTU,
You seem to have a real bee in your bonnet about pluto, you don’t ever seem to argue for the promotion for the eleven other currently recognised dwarf planets in the kuiper belt or the two in the asteroid belt, why not? what is so special about Pluto?

By: JMW

JMW — Sun, 20 Feb 2011 13:54:16 +0000

“And the Earth is accompanied by the Moon! That always amazed me.”

Isaac Asimov wrote a Black Widowers story called “The Missing Item” which…hmm…well, it’s a factor.

By: Jabjabs

Jabjabs — Sun, 20 Feb 2011 05:09:23 +0000

It’s images like this that make you realize just how empty space really is. Very impressive indeed.

By: Messier Tidy Upper

Messier Tidy Upper — Sun, 20 Feb 2011 04:15:07 +0000

@ ^ réalta fuar : Good point – I think a lot of astronomers would have strongly disagreed with the anti-Pluto IAU definition before it was made and a lot still do.

I think a majority of the public also disagree to the point where I expect (& yes hope) the IAU edict gets ignored and disdained in much the same way as many Catholics ignore some of the Pope’s silly decrees on contraception, etc ..

If everyone ignores the IAU definition and no one uses it then I think that would be a great thing. Hopefully, it will lead to them recognising that they’ve made a huge blunder and then fixing it. Let’s have mass civil disobedience against the IAU planet-killers I say!

@34. DrFlimmer :

@ Pete Jackson
Q: If a dwarf star is still a star, why is a dwarf planet not a planet?
Especially, since every star is a dwarf star in its lifetime. Basically every star on the main sequence is a dwarf star (if I remember correctly).

Your memory is indeed correct – and I couldn’t agree more!

@36. Gary & 38. JB of Brisbane : Yes indeed.

By: réalta fuar

réalta fuar — Sun, 20 Feb 2011 02:25:24 +0000

To quote Mke Brown (before he went all political correct): “why should Pluto be considered a planet? Because 6 billion people think so.” Funny how he changed his tune once a few people decided he wasn’t the discoverer of the tenth planet after all.

By: Tobin Dax

Tobin Dax — Sat, 19 Feb 2011 23:58:52 +0000

All four Galilean moons are visible around Jupiter. How easily they can be seen always amazes me.

By: JB of Brisbane

JB of Brisbane — Sat, 19 Feb 2011 23:52:45 +0000

“Pale Grey Dot” – somebody had to say it.
Also from the man himself, by way of Symphony of Science –
“How lucky we are to live in this time – the first moments in human history when we are, in fact, visiting other worlds.”

By: Brian

Brian — Sat, 19 Feb 2011 20:59:03 +0000

Just to be pedantic … the reading of Pale Blue Dot is not from Cosmos– whoever made this video used the Vangelis piece that is best known as the Cosmos theme, but Sagan wrote (and recited) these words years after Cosmos aired. Pale Blue Dot (the book) really would have made a great second series, I think.

By: Gary

Gary — Sat, 19 Feb 2011 17:34:46 +0000

That bit from Sagan never fails to bring a tear to my eye. He had SUCH a way with words.

By: flip

flip — Sat, 19 Feb 2011 14:30:43 +0000

#10, 30, and #31

I’m currently making scale planet puppets for a project – the first time I’ve ever made or even seen scale models – and not only is it fun, but it certainly does drum home how big/small everything is. My intention was to make finger puppets, but you quickly realise that Mars is way too small for that, and that Jupiter and Saturn are way too big. It’s an interesting exercise as a puppet maker, because of the scale, so instead of just finger puppets, I have all different types of puppets but in ‘planet’ form and to scale.

Fun and educational!

By: DrFlimmer

DrFlimmer — Sat, 19 Feb 2011 10:26:58 +0000

@ Pete Jackson

Q: If a dwarf star is still a star, why is a dwarf planet not a planet?

Especially, since every star is a dwarf star in its lifetime. Basically every star on the main sequence is a dwarf star (if I remember correctly).

By: Pete Jackson

Pete Jackson — Sat, 19 Feb 2011 09:29:52 +0000

@27HP: Earth-moon were the only double planet until Charon was discovered in 1978, making Pluto-Charon a closer (both in size and distance) double planet than Earth-moon. But Pluto got demoted later to a dwarf planet, so we now have to consider dwarf planets in order to find other double planets.

Q: If a dwarf star is still a star, why is a dwarf planet not a planet?

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 19 Feb 2011 08:55:14 +0000

Pluto~wise the debate from the last “Planet X found?” thread continues here :

http://blogs.discovermagazine.com/badastronomy/2011/02/14/no-theres-no-proof-of-a-giant-planet-in-the-outer-solar-system/#comment-359839

with my (somewhat belated sorry) answers – comment #135 onwards – to CB & andy if anyone’s interested.

By: molybdenumfist

molybdenumfist — Sat, 19 Feb 2011 05:30:47 +0000

I have some pictures on my office wall of the Earth and Moon to scale and 3m apart. The sun would be a bit over a kilometer down the road at that scale. It makes you appreciate how small this rock is and how much black there is in between.

In Melbourne here we also have a 1:1 billion scale model of the solar system that you can walk or ride a bike along too:
http://www.portphillip.vic.gov.au/default/CommunityGovernanceDocuments/Solar_System_-_Self_Guided_Walk.pdf

By: Bob

Bob — Sat, 19 Feb 2011 03:41:14 +0000

@#10 Nick Dvoracek
“A moon globe which would be in scale with a 12 inch Earth globe would be a3.25″ in diameter.

Virtually every classroom in the world has a 12 inch earth globe. The separation at this scale would be 30 feet, about the dimensions of the average classroom allowing a really accurate display of an accurate model of the system.

I think this would be a really cool demonstration of the scale of the earth moon system. I’d buy at least a couple.”

What an incredible idea! The globes could easily be strung from the ceiling. This idea has great merit-every schoolroom should have an Earth-Moon System in scale. Then kids could really see the scale of the galaxy, which should help them grasp the scale of the cosmos (or at least our solar system and galaxy).

By: dustycrickets

dustycrickets — Sat, 19 Feb 2011 03:40:55 +0000

OT…sorry Phil…..but have you seen this…

“Measles Outbreak Triggered by Unvaccinated Child”

http://news.health.com/2010/03/22/measles-outbreak-triggered-unvaccinated-child/?pkw=outbrain-ha

By: JeremyC

JeremyC — Sat, 19 Feb 2011 02:29:32 +0000

“No, every clear night we’re on the observation deck of our own spaceship, if we want to be.” – Vagueofgodalming

An exquisite quote. Thanks!

By: HP

HP — Sat, 19 Feb 2011 01:53:55 +0000

I love pictures of the Earth and Moon together (Messenger’s earlier pic is my desktop).

As long as we’re reclassifying celestial bodies, can we just call the Earth-Moon system a binary planet? You know, Sol C1and Sol C2?

Earth-moon really is quite a bit different than the situation with the other solar planets.