Astronomy Picture of the Day 9-09-03

NASA ^ | 9-09-03 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 September 9

A Gemini Sky
Credit: Gemini Observatory, Peter Michaud & Kirk Pu'uohau-Pummill

Explanation: Where will Gemini take us tonight? It is dusk and Gemini North, one of the largest telescopes on planet Earth, prepares to peer into the distant universe. Gemini's flexible 8.1-mirror has taken already effectively taken humanity to distant stars, nebulas, galaxies, and quasars, telling us about the geometry, composition, and evolution of our universe. The above picture is actually a composite of over 40 images taken while the Gemini dome rotated, later adding an image of the star field taken from the same location. The Gemini dome is not transparent -- it only appears so because it rotated during the exposures of this image. The constellations of Scorpius and Sagittarius can be seen above the dome, as well as the sweeping band of our Milky Way Galaxy, including the direction toward the Galactic center. Gemini North's twin, Gemini South, resides in Cerro Pachón, Chile. This night, 2003 August 19, Gemini North took us only into the outer Solar System, observing Pluto in an effort to better determine the composition of its thin atmosphere.

Tomorrow's picture: Aurora Over Clouds

[petuniasevan]

Gemini North in daylight:

I once heard someone describe the summit of Mauna Kea (where this telescope and many others are located) as "this is NOT Hawaii!"
Winter on Mauna Kea summit at Gemini North:

Forecast for Mauna Kea summit - note the temps are in Celsius. 0 is 32, 1 is 33.8, 2 is 35.6, 3 is 37.4.

Latest Forecast for Mauna Kea Observatories 5 pm HST Monday 08 September (0300 UTC Tuesday 09 September) 2003
Warnings
None

Cloud Cover and Precipitation Forecast Clear skies and dry summit air are expected to last through the night.

Summary of Key Meteorological Variables Summit temperatures will be near 2.75 C tonight and 1.75 C tomorrow morning. Precipitable water is expected to be in the 1.35 to 1.85 mm range tonight and 1.15 to 1.65 mm range in the morning hours. Winds will be from the east-northeast at 15 to 25 mph, with shear between 25 to 35 mph.

Discussion The tradewind inversion will continue to keep the air above 6 to 8 thousand feet quite dry through the most of Tuesday night. The inversion is slated to weaken and lift to 10 or 11 thousand feet on Wednesday. This will likely increase afternoon clouds/humidity for that day, as well as raise the odds on fog to about 10% for that evening. If there is any fog, it will be very short-lived as dry air should return by 7-8 PM that night, at the very least.

No high clouds will be within 500 km of the summit through tomorrow evening. On Wednesday very scattered cirrus is expected to approach from the west, south, and to some extent the east. These clouds are still not projected to come within 250 km of the summit for that morning and night, in which case cloud cover will not exceed 5%.

Summit winds are expected to drop from 15 to 25 mph for tonight to 5 to 15 mph by Wednesday. It is projected to increase back up to 10 to 20 mph by later that night and to 15 to 25 mph by Thursday. Winds will start out from the east-northeast, but will be backing to northerlies by late tomorrow night, eventually becoming variables on Wednesday morning. By Wednesday afternoon and into that night it is expected to take on a more southerly component.

Minimum overnight summit temperatures will be near 1 to 2 C during the next three nights.

The temperature at the summit reached a low of 12 degrees on May 17, 1979!

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Gemini uses adaptive optics to enable better imaging through Earth's turbulent atmosphere.

[petuniasevan]

[BossyRoofer]

Great work, keep it up! By the way Mars is sure something to see here in duchesne utah.

[Soaring Feather]

Thanks so much for the ping.

[firewalk]

Thanks for the ping

[sistergoldenhair]

Thanks for the ping.

[GATOR NAVY]

Mars early evening last night was very close to the Moon-maybe 1/10th Moon diameter or less. Will Mars be passing behind the Moon in the next few days or did it already?

[petuniasevan]

Yes, the Moon occulted Mars 9-09-03. It was only visible from Northeast Asia.

I see you're in Japan somewhere. I ran my Starry Night software for Tokyo, Japan, and the distance from Mars to the Moon's edge at was about 5 or 6 minutes of arc (the Moon subtends on average 30 seconds of arc). Closest approach was about 8:35 PM Tokyo standard time.

The Moon did occult Mars on July 16/17 as seen from the southern tip of Florida and the Caribbean. See the 7-24 APOD.

Here is a resource for learning about occultations of all sorts: IOTA.

[GATOR NAVY]

Thanks for the info. Yes, I'm just southwest of Tokyo. When I first saw the Moon come up it was low enough to still be still orange, probably 5 degrees altitude. Mars was at about the 8 o'clock position maybe half a diameter away. The last time I looked it was at the 6 o'clock position and much closer. That would have been sometime between 8:00 and 9:00 p.m. I wish now I'd paid closer attention.

Actually, the weather's been so cloudy here this summer I couldn't remember the last time I'd seen the Moon. And even on clear nights being so close to Tokyo I don't see anything but planets and a few first magnitude stars.