Why is Jupiter so bright right now?

PhanthomJay

I couldn't help notice how bright Jupiter appeared last night with the crescent moon and Venus by her side. It appeared almost as bright as Venus.

Question: Since Jupiter is on the other side of the sun from Venus right now (right?), shouldn't it be rather dim? I mean it's distance from us must be way farther out than when

davenn

no thats not correct

Jupiter at the moment is at its closest to earth for some decades, from memory last closest approach was ~ 1963.
Over the last couple of months Jupiter has been great to view through the telescope

The Earth and Jupiter are on the "same side of the sun" not opposite sides

Dave

PhanthomJay

Oh, no wonder why its so bright! I thought that since we can see Jupiter and Venus at the same time side by side, and that since Venus is closer to the sun than Jupiter, with us in between, that if we see them side by side, Jupiter must be presently on the other side of the sun from Venus, but now I realize I did some bad geometry. Thanks for the response.

SHISHKABOB

from here: http://www.fourmilab.ch/cgi-bin/Solar/action?sys=-Sf

Chronos

Three basic factors determine apparent brightness of a planet - its angular diameter, albedo and distance from the sun. Venus has jupiter beat slightly on both counts. At closest approach Venus has a apparent diameter of about 65" whereas Jupiter has an apparent diameter of about 50". The albedo of Venus is about .66 whereas Jupiter is only around .5. Jupiter is around 7 times more distant than Venus is from the sun, so the sunlight reflected by Jupiter is considerably dimmer than that reflected by Venus.

DaveC426913

Four:

Its phase. According to that diagram, Jupiter is a gibbous (or whatever gibbous is called for non-Moon bodies), near full phase.

This affects inner planets much more than outer planets though. We can often see cresent or even new inner planets but we'll never see a crescent outer planet.

Drakkith

Currently almost 4 months has passed since opposition and Jupiter is now magnitude -2.2, which is about 5 times dimmer than Venus which is magnitude -4.3. Jupiter is almost at its dimmest point.

Chronos

Jupiter is always 'full moon' as viewed from earth, only bodies nearer than earth to the sun have phases.

DaveC426913

True, Jupiter cannot be crescent or new, but it can be gibbous.

semiscientist

Please explain this to me. A planet is not emitting light, right, only defecting it, correct?
Why would a planet like Jupiter reflect so much light as to make it appear as a star?
How come some planets light up completely from the supposed reflection, but other bodies do not? I am no scientist just an inquisitive mind. I do not accept the given explanations. Can someone enlighten me?
Are we being told the truth about stars and planets? Seriously....???
Venus and Jupiter supposedly shine very bright some nights. Why is that, that they appear as stars? How can that be, by plausible explanation?

And, how does anyone know the sun is 93 million miles from earth?
Who measured it? Seriously?

Do people believe this kind of stuff because of some kind of "consensus"?
Was there not a consensus in the 12th century that the earth was flat?

davenn

REFLECTING light :) yes

What other bodies ?? name one or two


All the planets appear as "stars' that is ... pinpoints of light its when you look at the planets with a modest telescope with say an 8" mirror you can discern an actual disk for at least mercury to Uranus. Neptune is a little trickier without a larger scope. I personally havent viewed Neptune ( not that I recall anyway)

as far as distance to the sun goes....
a quote from the net....
"Another method was explored in 1672 by Cassini and Richer: they measured the parallax (i.e. the variation in angle when seen from different places) under which Mars was seen in Cayenne and Paris, at the moment of opposition. From this, they deduced the distance Earth-Mars. Then, using the Kepler law

a^3 / p^2 = constant
(where a is the distance between the planet and the Sun, and p the sideral time)
they could figure out what was the distance to the Sun."


OF course we do, we believe it cuz there's tons of scientifically supporting evidence. There's been telescopes and other instruments pointing into space for at least 2 centuarys

I cant do the maths for you ... its not my forte ... but even long long ago, those much mathematically inclined worked out those things combined with lots of night sky observations

cheers
Dave

Bandersnatch

(emphasis mine)
Isn't that a bit redundant? After all, angular diameter is a function of the distance from the sun(and the actual diameter), so once we've taken the one into account, there's no point in correcting for the other.
It'd make sense to count both, I suppose, had the interplanetary medium been dense enough to disperse appreciable amounts of light on its way toward us, but it's hardly the case.

@Semiscientist: it's the same reason why it's easier to see a white cat in your room shining with the reflected light of a 100W lightbulb than it is to see another 100W lightbulb five blocks away*.
The planets are highly reflective(some of them at least), and close to both the source of light(the Sun) and the observer(us).


*probably not to scale

semiscientist

okay then, (Bandersnatch), what causes a planet to reflect light?
Seriously, not trying to egg anyone on. I have no scientific background just a curious mind.

AND, this just means the light was strong enough (close enough) to illuminate the cat, but if I were near the cat and the room which was illuminated, I would see a lot more illumination.
But we are talking about darkness, at night.
Why would an object thousands and thousands of miles away, reflect light from a distant star, unless it had some reflective capabilities? and if so...what are they?

semiscientist

But dozens of scientists will tell you free energy is impossible according to known physics, yet Nikola Tesla proved them all wrong over a 100 years ago, so I do not take scientific method for fact. I prefer an explanation that makes common sense to me.

semiscientist

Bandersnatch...as you can see, I just joined. I'm no scientist at all. I'm just very curious and wanted to learn. Please understand, and help out, if you will. I don't mean to sound redundant, but i'm scientifically "stupid". I admit.

someGorilla

Maybe you're not aware that nearly EVERYTHING reflects light. Otherwise you couldn't see anything! When you see a person in front of you, what you are actually seeing is the light reflected by her body (or clothes, as the case might be ) towards your eyes. Nothing strange about planets here. That is what "seeing" is!

davenn

he didnt prove anything like that ...
Dont get off topic !!! thats totally irrelevent and discussions on such are not permitted on the this forum

Answer my question from my previous post please

Dave