銀星砂 星之生活 | Starlife @ Stardust Sand

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[2007-03-21]

2007-03-19 日偏食


因為一份的堅持,因為一份的預感,天文台的預測縱然多差,還是完成了日偏食觀測的前期工作,包括了宣傳、易拉架、瀘光鏡製作、編寫網上直播網頁的系統…

早上6時,天下著雨。

7時,也是下雨。回到了天文館,還是展開了預備工作,其實大可以宣報一句「因天氣欠佳,活動取消」,便可以什麼也不做,但或許是那一份預感,下著雨還是沒放慢步伐。

偶爾間,看了天文台的雷達資料,看見一條分明的雨帶正橫越香港,心算一下速度,再次支持自己的想法,一定會好天!

9時,天依然下著雨,日食9時08開始了。但很快,雨停了不久,天色有所改變,天亮了起來,希望出現了。

雨過後果然天晴,天真的開了起來,辛苦寫成的網上直播立派用場。那一份由無到有,那一種看見太陽神奇地咬去一口的喜悅,在所有人的臉上全流露了出來。被形容為神蹟的天晴,好讓看到日食的大部份。

南華早報的攝影記者本也預算不可能看見什麼,怎料奇蹟果然出現,拍了很多相片。我想也沒想過,這次的日偏食,居然成為了3月20日SCMP的COVER STORY。

要知道,我從未看過天文的新聞在一份報章的頭版出現過!而且實在感到萬分榮幸,因為這報導是由我束成的。以往訪問了很多,但報導往往只佔很少或者錯漏百出的經驗實在太多了。

計算一下,當天有整整100人在天文館中看到了日食,看到了很多被impressed了的樣子,或許這就是我得到的回報。

多謝上天,多謝大家相信我的堅持。




[2007-03-21]

網頁更新


已經有好一陣子沒有真真正正更新這裡,其實不止「星之生活」這版,整個銀星砂的網站,由Pic of the Day至銀星砂的天文版,都有數個月沒有真正去更新,請讓我首先先說聲「對不起」。

忙或許是一個原因,但另一個主要原因或許是因為懶,要維持一個這樣的網站,的確要花不少時間,有一刻停了下來,便會想再休息多一會。早前曾嘗試去番新這個網頁,讓它變得更方便(這是在我編寫這網站背後的programming的hidden工作問題了,一向在讀者角度是透明的),還有,我其實不太滿意這網站的設計,想重新設計。但這樣的改動,我想我要整整一個月時間才可以完成,在早前較忙的日子裡,實在很難抽到時間,我的確開了頭,但結不了尾。

現在,雖然不是空閒了(手上也有數個大計劃要進行),但還是覺得不該丟下這網站置之不理,所以現在正著手進行更新的工程,最近改良了的是留言的系統,因為早前有大量的spam,現在改良了,希望可以避免了無謂的留言。

若果可以,還望大家多點給予意見,關於版面設計或是內容也可以。希望銀星砂這網站可以不斷改進,越來越好。謝謝大家。




[2007-02-17]

Watermarks on Mars


NASA Mars Orbiter Sees Effects of Ancient Underground Fluids

Liquid or gas flowed through cracks penetrating underground rock on Mars, according to a report based on some of the first observations by NASA's Mars Reconnaissance Orbiter. These fluids may have produced conditions to support possible habitats for microbial life.

These ancient patterns were revealed when the most powerful telescopic camera ever sent to Mars began examining the planet last year. The camera showed features as small as approximately 3 feet across. Mineralization took place deep underground, along faults and fractures. These mineral deposits became visible after overlying layers eroded throughout millions of years.

Chris Okubo, a geologist at the University of Arizona, Tucson, discovered the patterns in an image of exposed layers in a Martian canyon named Candor Chasma. The High Resolution Imaging Science Experiment camera aboard the orbiter took the image in September 2006.

"What caught my eye was the bleaching or lack of dark material along the fracture. That is a sign of mineral alteration by fluids that moved through those joints," said Okubo. "It reminded me of something I had seen during field studies in Utah, that is light-tone zones, or 'haloes,' on either side of cracks through darker sandstone."

"This result shows how orbital observations can identify features of particular interest for future exploration on the surface or in the subsurface or from sample return. The alteration along fractures, concentrated by the underground fluids, marks locations where we can expect to find key information about chemical and perhaps biologic processes in a subsurface environment that may have been habitable," said Alfred McEwen, principal investigator for the camera at the University of Arizona, Tucson.

The haloes visible along fractures seen in the Candor Chasma image appear to be raised slightly relative to surrounding, darker rock. This is evidence that the circulating fluids hardened the lining of the fractures, as well as bleaching it. The harder material would not erode as quickly as softer material farther from the fractures.

"The most likely origin for these features is that minerals that were dissolved in water came out of solution and became part of the rock material lining the fractures. Another possibility is that the circulating fluid was a gas, which may or may not have included water vapor in its composition," Okubo said.

Similar haloes adjacent to fractures show up in images that the high-resolution camera took of other places on Mars after the initial Candor Chasma image. "We are excited to be seeing geological features too small to have been noticed previously," Okubo said.

"This publication is just the first of many, many to come. The analysis is based on test observations taken even before the start of our main science phase. Since then, Mars Reconnaissance Orbiter has returned several terabits of science data, sustaining a pace greater than any other deep space mission. This flood of data will require years of study to exploit their full value, forever increasing our understanding of Mars and its history of climate change," said Richard Zurek, project scientist for the Mars Reconnaissance Orbiter at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Okubo and McEwen report these findings in the Feb. 16 edition of the journal Science. Images showing the haloes along fractures are available on the Web at:

http://www.nasa.gov/mission_pages/MRO/news/20070215.html

The Jet Propulsion Laboratory manages the orbiter mission for NASA’s Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The University of Arizona operates the High Resolution Imaging Science Experiment camera. Ball Aerospace and Technology Corp., Boulder, Colo built the camera.


:: Link



[2007-01-08]

Catching Cosmic Clues


這年的第一期Science又是天文的Special Issue
今期是 Particle Astrophysics
而且罕有地只有Perspectives

剛巧星期六科學館有中微子的講座
香港的中微子研究
巧合


:: Link



[2006-11-08]

2006 水星凌日 路邊天文觀測活動


2006 水星凌日 路邊天文觀測活動

可觀自然教育中心暨天文館主辦

日期: 2006年11月9日 (星期四)
時間: 早上 6:00 - 8:30
地點: 西貢惠民路西貢海濱公園對開海傍
  (西貢公眾碼頭側)
費用: 全免
名額: 不限


水星凌日天象簡介:
水星凌日是一項罕見的天文現象。每當水星運行至太陽與地球中間,三者大致連成一直線時, 便會看見水星於太陽表面經過的情況,此現象稱為水星凌日。由於地球軌道與水星軌道並不在 同一平面上,而是有7度的夾角,所以並不是每次三者成日水地的排列都會出現水星凌日。 平均每100年只會出現13次的水星凌日上次是發生在2003年,但由於下兩次於2016及2019年出現時, 香港都位於無法觀測的地區。因此若錯過了是次之天象,香港市民要待到26年後的2032年才可再看見水星凌日。


水星凌日發生條件示意圖

以下是11月9日水星凌日的時間表:
凌始外切(第一接觸) 03時12分 [香港不可見]
凌始內切(第二接觸) 03時14分 [香港不可見]
日出 06時31分
凌終內切(第三接觸) 08時08分
凌終外切(第四接觸) 08時10分



2006年11月9日水星凌日路徑圖

觀測方法:
是次水星凌日於日出前的凌晨時份已開始發生,因此6時32分日出後水星已走了大半的凌日路程。當天日出於東方偏南18度,直至凌日於8時10分完結太陽會升至仰角23度左右。 由於水星的視直徑僅達10角秒,最理想的觀測方法是利用裝置了太陽濾鏡的小型天文望遠鏡進行觀測。利用投影儀或針孔照相機作投影法、加上太陽濾鏡的雙筒望遠鏡或透過太陽濾光片直接目視觀測亦可。

請注意:切記不要在沒有任何減光情況下直接目視太陽,因為太陽強烈的光線以及有害的紫外線都會永久損害視力。即使是在日出時看來暗淡的太陽亦不可直視。任何情況都必須使用絕對安全的保護措施才可觀測太陽。最安全是以投影法觀看,用專用的太陽濾光鏡亦可。以墨水倒影,煙薰黑的破璃、已曝光的底片、光碟片、太陽眼鏡等觀看都是十分危險的方法。


1999年水星凌日 [Credit: Brian Handy, TRACE Project]


活動內容簡介:
本館將於西貢海濱公園對開海傍設置多台天文望遠鏡,在導師輔助下,讓市民自由欣賞天象。 現場附設水星凌日天象展覽,即場講解天象成因及解答市民問題,亦會為有興趣拍攝的市民提供意見和協助。同時歡迎香港的天文同好帶同望遠鏡一同參與。

參加辦法:
無須報名,參加者自由前往,費用全免

更多有關水星凌日的資料:
Shadow & Substance Homepage

警告:
切勿直接觀測太陽,否則會導致失明。



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