Starship Asterisk*

Live: Watching for Venus to Cross the Sun

Explanation: Today Venus moves in front of the Sun. One way to follow this rare event is to actively reload the above live image of the Sun during the right time interval and look for an unusual circular dark dot. The smaller sprawling dark areas are sunspots. The circular dot is the planet Venus. The dark dot will only appear during a few very specific hours, from about 22:10 on 2012 June 5 through 4:50 2012 June 6, Universal Time. This transit is the rarest type of solar eclipse known -- much more rare than an eclipse of the Sun by the Moon or even by the planet Mercury. In fact, the next transit of Venus across the Sun will be in 2117. Anyone with a clear view of the Sun can go outside and carefully view the transit for themselves by projecting sunlight through a hole in a card onto a wall. Because this Venus transit is so unusual and visible from so much of the Earth, it is expected to be one of the more photographed celestial events in history. The above live image on the Sun is being taken by the Earth-orbiting Solar Dynamics Observatory and can be updated about every 15 minutes.

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Oooh, n-i-c-e puddy tat!!

It will be an even more interesting photographic and possibly scientific scene if Venus passes directly over a sunspot.

I'll have to check on it from time to time!

Such a cool APOD!!!

Why do the hottest parts of sun appear as black dots? Why not white? Wanted always to ask

Moonlady wrote:Why do the hottest parts of sun appear as black dots? Why not white? Wanted always to ask :!:

Sunspots are cooler than the surrounding areas, which is why they appear dark in continuum (white light) images.

Great APOD!
Where is SDO in the sky? Will it have the same view of the transit as we will have here on Earth?

Chris

For those of you who haven't noticed, today's APOD is a semi-live feed of the Sun from NASA's SDO. It's delayed about 30-45 minutes, updated every 15 minutes (you have to refresh). You will be able to view the transit on APOD, via SDO. For 12 separate live feeds of the event, visit Sun-Earth Day: 2012 Transit of Venus.

Clinker wrote:Where is SDO in the sky? Will it have the same view of the transit as we will have here on Earth?

SDO is in a circular, geosynchronous Earth orbit at an altitude of 36,000 kilometres (22,300 mi), at 102° W longitude, inclined at 28.5°.

bystander wrote:

Clinker wrote:
Where is SDO in the sky? Will it have the same view of the transit as we will have here on Earth?

SDO is in a circular, geosynchronous Earth orbit at an altitude of 36,000 kilometres (22,300 mi), at 102° W longitude, inclined at 28.5°.

The SDO will begin begin today's 2012 Transit trailing behind the Earth in it's orbit by about a half an arcminute as seen from the sun.

Hence the SDO should observe essentially the same transit only
it will see it starting about 10 minutes sooner (~ 22:00 on 2012 June 5 Universal Time).

bystander wrote:
For those of you who haven't noticed, today's APOD is a semi-live feed of the Sun from NASA's SDO. It's delayed about 30-45 minutes, updated every 15 minutes. You will be able to view the transit on APOD, via SDO. For 12 separate live feeds of the event, visit Sun-Earth Day: 2012 Transit of Venus.

Art (semi-live) Neuendorffer

is anyone else saving all the images to make a gif?

SDO's Venus transit page includes a bogus transit simulator by sunaeon showing Venus taking crazy paths (depending on your locale) across the sun's disk!
I am reminded of Velikovsky's Worlds in Collision.
http://venustransit.gsfc.nasa.gov/

Chris Peterson wrote:

Moonlady wrote:Why do the hottest parts of sun appear as black dots? Why not white? Wanted always to ask

Sunspots are cooler than the surrounding areas, which is why they appear dark in continuum (white light) images.

Thanks, I must have misread it! Glad to know now!

Not looking good in south central Alaska. It's overcast at just over 4 hours before start. Hopefully it will burn off this afternoon.

Moonlady wrote:Why do the hottest parts of sun appear as black dots? Why not white? Wanted always to ask

It is interesting to consider that the temperature of the sunspots is about equal to the temperature of red giants and red dwarfs. So when our Sun becomes a red giant, all of it will become as "dark" as the sunspots. On the other hand, the Sun will grow horrendously big, and its total energy output will increase. We will be fried, for sure!

As for the dark sunspots, there are often active regions close to them which emit a lot of UV light and also a bit of X-rays. But these active regions, which are very hot, don't show up well in optical images. I can't see any of them in today's APOD. However, Moonlady, when there are no sunspots on the Sun there are also no (or at least very few) active regions, and the Sun's total energy output is a little lower than usual.

I agree with those who think that this is a very interesting APOD, and it is an extremely helpful service for those who want to see the transit of Venus but can't see it due to unfavorable weather.

Ann

Ann wrote:It is interesting to consider that the temperature of the sunspots is about equal to the temperature of red giants and red dwarfs. So when our Sun becomes a red giant, all of it will become as "dark" as the sunspots.

It's also interesting to consider that we're only seeing these spots as dark because of the contrast with their surrounds. If the whole Sun had the surface brightness of a sunspot, it would still burn out the back of your eye if you looked at it for very long. You'd still think that it looked white. Sunspots actually are very bright.

Ann wrote:

Moonlady wrote:Why do the hottest parts of sun appear as black dots? Why not white? Wanted always to ask

It is interesting to consider that the temperature of the sunspots is about equal to the temperature of red giants and red dwarfs. So when our Sun becomes a red giant, all of it will become as "dark" as the sunspots. On the other hand, the Sun will grow horrendously big, and its total energy output will increase. We will be fried, for sure!

As for the dark sunspots, there are often active regions close to them which emit a lot of UV light and also a bit of X-rays. But these active regions, which are very hot, don't show up well in optical images. I can't see any of them in today's APOD. However, Moonlady, when there are no sunspots on the Sun there are also no (or at least very few) active regions, and the Sun's total energy output is a little lower than usual.

I agree with those who think that this is a very interesting APOD, and it is an extremely helpful service for those who want to see the transit of Venus but can't see it due to unfavorable weather.

Ann

That is what I have red, dark spots being the active regions.
But I thought that activity let them emit more energy, more heat and light and therefore white spots...
But they are dark...
The active regions are still cooler than the sun itself so they appear dark okey that is an explanation.

Why do we see red giants red, when our sun will appear dark as its spots when it will turn into
a giant? Is it because our sun is meassured with another color scale than red giants?
Will the dark spots be seen red because there is no bright sun anymore?

Arrrgggg: Still cloudy in central Florida. Will be tuning in to the live feeds.

Here's my evening....
Paint one side of a kitchen cabinet door.
Go hit APOD reload
Paint other ide of a cabinet door
Go hit APOD reload
Paint a different cabinet foor.
Reload APOD...

I have 17 cabinet doors. That should work out close to right, yes?

Bought a special solar filter, and its cloudy and raining in Central Idaho.

Cloudy @ Goddard.

Why are there dark rings on the dark side of Venus? You can see them in the videos here http://venustransit.gsfc.nasa.gov/
Here is the particular movie http://venustransit.gsfc.nasa.gov/data/ ... se/ingress

Edit:
And Venus seems to be transparent. You can see the edge of the sun through Venus.

Clear in Houghton, Michigan. Seeing the spot!
- RJN

Cloudy in OKC, having to rely on the internet.