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Astronomers

A group for people who enjoy the stars. :)

Members: 165
Latest Activity: Sep 7

Discussion Forum

Possible shape of the universe

Started by Donald L. Engel. Last reply by Kiljoy616 Mar 18. 9 Replies

All things Pluto

Started by Joan Denoo. Last reply by Gerald Payne Sep 17, 2015. 2 Replies

The Five Planets in the Sky.

Started by Visvakarman Svetasvatara-Upanish Jun 17, 2015. 0 Replies

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Comment by Gerald Payne on March 19, 2015 at 3:13pm

With Philae now receiving twice as much solar energy as it did last November when it finally came to rest in a shaded spot on Comet 67P, the communication unit on the Rosetta orbiter has now been switched on to call the lander. Although it is probably still too cold for the lander to wake up, the prospects will improve with each passing day.

Waking up at the right temperature and energy

Several conditions must be met for Philae to start operating again. First, the interior of the lander must be at least at –45ºC before Philae can wake up from its winter sleep. At its new landing site – Abydos – only a little sunlight reaches Philae, and the temperatures are significantly lower than at the originally planned landing location. In addition, the lander must be able to generate at least 5.5 watts using its solar panels to wake up.

As soon as Philae ‘realises’ that it is receiving more than 5.5 watts of power and its internal temperature is above –45ºC, it will turn on, heat up further and attempt to charge its battery.

Contact during comet daytime

Once awakened, Philae switches on its receiver every 30 minutes and listens for a signal from the Rosetta orbiter. This, too, can be performed in a very low power state.

It could be that the lander has already woken up from its winter sleep some 500 million kilometres away from Earth, but does not yet have sufficient power to communicate with Rosetta, which relays Philae’s signal back to Earth. Philae needs a total of 19 watts to begin operating and allow two-way communication. Between 12 and 20 March, the Rosetta orbiter is transmitting to the lander and listening for a response. The most likely time for contact is during the 11 flybys where the orbiter’s path puts it in a particularly favourable position with respect to the lander during comet ‘daytime’ – when Philae is in sunlight and being supplied with power by its solar panels. Communication will be attempted continuously because Philae’s environment could have changed since landing in November 2014.

Comment by sk8eycat on March 19, 2015 at 2:26am

We had a half-hour rainstorm a couple of hours ago.  That was the 4th or 5th shower we've had in the last 3 months.  We are in a water crisis, and nobody (so far) has done Jack Schidt about water rationing....or anything else.

I've never understood why we didn't start building desalinization plants decades ago.  There a whole effing OCEAN out there!

Comment by sk8eycat on March 18, 2015 at 9:17pm

Patricia: I have always wanted to see the Northern Lights with my own eye, but never had a chance.  We're WAY too far south, and it's overcast right now anyway.

Have YOU been able to see the Light Show this week?

Comment by Visvakarman Svetasvatara-Upanish on January 30, 2015 at 1:35pm

I live in California, and Jupiter has been out for the last couple days, probably longer. I'm new to star gazing. And according to this site, I've been missing a lot more:
http://earthsky.org/astronomy-essentials/visible-planets-tonight-ma...

Comment by Idaho Spud on November 9, 2014 at 8:45am

The predicted merging of Andromeda & Milky way is interesting.  I'd like to be around 8 billion years from now to see it.

Comment by Joan Denoo on November 8, 2014 at 6:13pm

I think so, too. 

Comment by Loren Miller on November 8, 2014 at 5:42pm
That is positively gorgeous, Joan!
Comment by Joan Denoo on November 8, 2014 at 4:29pm

Gemini legacy - photo of day   

Polar Ring Galaxy NGC 660   beautiful

"a sharp composite of broad and narrow band filter image data from the Gemini North telescope on Mauna Kea. Over 20 million light-years away and swimming within the boundaries of the constellation Pisces, NGC 660's peculiar appearance marks it as a polar ring galaxy. A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dust orbiting in rings nearly perpendicular to the plane of the galactic disk. The bizarre-looking configuration could have been caused by the chance capture of material from a passing galaxy by a disk galaxy, with the captured debris eventually strung out in a rotating ring. The violent gravitational interaction would account for the myriad pinkish star forming regions scattered along NGC 660's ring. The polar ring component can also be used to explore the shape of the galaxy's otherwise unseen dark matter halo by calculating the dark matter's gravitational influence on the rotation of the ring and disk. Broader than the disk, NGC 660's ring spans over 50,000 light-years."

Comment by Joan Denoo on June 22, 2014 at 4:11pm

Persistent Saturnian Auroras 
Image Credit: J. Clarke (Boston U.) & Z. Levay (STScI), ESANASA

Astronomy Picture of the Day

2014 June 22 
Comment by Lillie on May 16, 2013 at 7:53pm

The solar eruption is not as amazing as the fact they can take a picture like this of a solar eruption.

 

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