venus and sun

Venus transit heralds Endeavour enterprise

MAKE a note in your diary. On June 6, something will happen that will not be repeated in your lifetime - unless you plan on living for another 105 years.

If it isn't cloudy, observers in Sydney will be able to watch the silhouette of Venus transiting across the sun.

The astronomical event occurs in pairs eight years apart. It happened in 2004, but after June's recurrence will not be seen again until December 11, 2117.

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Apart from the rarity of the transit of Venus, it has special significance for Australians.

Captain James Cook sailed for Tahiti on the Endeavour with the astronomer Charles Green to make observations of the transit on June 3, 1769. Once completed, his instructions from the Admiralty were to continue south to find the fabled ''Unknown South Land''.

The rest is history.

To mark the event, the HMB Endeavour replica operated by the Australian National Maritime Museum will follow in Captain Cook's wake on a voyage to Lord Howe Island to observe the June transit.

Interest in the voyage was so great that a ballot was held for the 35 working crew. A place cost $4000 ($8000 for the luxury of a cabin) and was eight times oversubscribed.

Tomorrow, the successful 35 will be drawn and they will be expected to fully participate in setting sail, climbing the rigging and manning the helm.

On board will be the Sydney Observatory astronomer Carlos Bacigalupo, who will assist with observations. ''From Lord Howe we will see the transit slightly earlier and there is a chance of slightly better weather,'' he said. ''The main reason to watch it is historical, but there is still some science to be learnt.''

The transit starts at 8am and finishes at 2.30pm. It should not be viewed with the naked eye, but can be looked at through an old X-ray print.

The only unknown is the weather. Participants will be hoping for a repeat of what Cook recorded in his ship's log. ''This day prov'd as favourable to our purpose as we could wish, not a Clowd was to be seen the whole day and the Air was perfectly clear … ''

Twice in a lifetime ... Venus and the sun during its 2004 transit.

冰河時期植物

2012年2月22日 星期三

冰河時期植物「復活」開花

果實藏俄凍土層3萬年 抽細胞培植

【明報專訊】俄國專家在西伯利亞長期凍土層，發現3萬年前冰河時期的果實，並成功令其「復活」開花，是歷來最古老的「重生」植物。以色列專家之前曾「種活」一顆儲存兩千年的棕櫚科植物種子，俄專家今次卻用上果實細胞進行培植，令更久遠的植物「復生」。新發現有望令更多埋藏凍土的絕種古生物重現人世。

俄羅斯科學院的研究報告稱，科學家在西伯利亞科爾梅亞河（Kolmya River）畔的凍土，即發掘出大量長毛象、長毛犀的更新世（Pleistocene，距今260萬至1萬年前）晚期土層，發現約70個3萬年前的松鼠地洞。這些洞穴距現時地面約20至40米，每個約足球大小，是松鼠為了在北極圈的夏季冷藏食物，在河畔尚未冰封的位置挖掘的。研究員古賓（Stanislav Gubin）稱：「這是天然冷藏庫。松鼠先在洞裏鋪乾草，再鋪動物毛髮，是完美儲藏庫。若好運，可望掘出冷凍松鼠組織，甚至引領我們複製長毛象。」

史前松鼠地洞掘出

部分洞穴藏有多達60萬顆種子及果實，大多來自蠅子草屬植物Silene stenophylla，惟後來颳起風雪令洞穴封死。從土地的垂直結冰狀況判斷，土層在冰封後從未融化，令果實和種子保存在-7℃低溫。研究員試圖令種子發芽，但未成功。他們於是從果實的胎座（placenta，製造種子的位置）抽取細胞，將細胞解凍「復活」。由於胎座含大量蔗糖與酚，可防止結冰破壞果實細胞。科學家成功以3個胎座進行「複製」，培植出36棵植物，大部分只需一顆成年細胞即可成功培育。

「翻生」植物在開花前的生長狀況，跟現存同種植物相同，但開出的花瓣卻比目前的同種植物幼細。研究員說，這些植物細胞能如此長壽，皆因當地輻射較低，減輕對果實基因的破壞。這些果實接收逾3萬年的伽瑪輻射水平，僅相當於一棵成功發芽的1300年蓮花種子。

火星冰封土壤可成「外星種子庫」

對於西方專家質疑俄國採用的果實是否真的年代久遠，研究員特別將果實胎座的種子進行「碳-14」年代測定，證明有3.18萬年歷史。丹麥基因專家維勒斯利夫（Eske Willerslev）稱，俄國的研究「理論上可行」，但取決於碳-14測定結果是否可靠。英國雷丁大學的種子專家默多克（Alastair Murdoch）則聲稱，罌粟種子在-7℃儲存160年後，只有2%種子能發芽，質疑研究結果。

若研究屬實，科學家可望把昔日生物「復生」，與現今生物作對比，揭開生物進化之謎，並將絕種生物重現人世。若火星等曾存在生物，甚至有機會從外星帶回冰封土壤複製外星生物。但負責帶領研究的吉利金斯基（David Gilichinsky）剛於周末心臟病發死亡，或令日後研究受阻。 紐約時報

俄羅斯科學家以3萬年前蠅子草屬植物Silene stenophylla的果實，培植出36棵植物。「重生」的植物花瓣比同種植物更幼細。

再開花的蠅子草屬植物Silene stenophylla

發現外星水世界

【明報專訊】天文學家證實發現一種新類型的行星——一個充滿蒸汽、有着厚厚大氣層的真正「水世界」。該星球名為GJ 1214b，距離地球40光年，體積比地球大，但小過木星，表面溫度可能高達200℃。哈勃望遠鏡已證實，它的大部分質量是水。圖為畫家筆下的水星球（體積較細者）圍繞恆星運行。

'white' black bear

2012年2月17日 星期五

罕見白熊現加國 全球僅200頭

【明報專訊】加拿大攝影師尼克倫（Paul Nicklen）在卑詩省一個森林拍到罕見的白熊，它全身白色，但並非北極熊，而是北美黑熊變種，稱為柯莫德熊（Kermode Bear）。

尼克倫稱，這種白熊全球僅剩200隻，比熊貓還罕有。他表示早前坐在該森林守候長達兩月，沒什麼發現，原以為要空手而回，豈料一隻白熊突然在距離他3呎遠的地方，抓着一條魚大快朵頤，於是尼克倫花了一整天，跟着那隻白熊穿越森林，近距離拍下牠的照片。 （每日郵報）

The rare bear bunch! Rare ‘white’ black beast captured on camera is not a polar bear

Standing its ground: The spirit bear comes into contact with another forest bear, which is a more traditional black colour

Synchronised swimming for bears? No, just an incredible reflection in crystal clear Arctic ice

清潔衛星

2012年2月17日 星期五

發射清潔衛星 掃太空垃圾

【明報】激烈的太空競賽換來一大堆太空垃圾，應怎樣善後？瑞士科學家日前宣布，最快2016年會發射全球首個清潔衛星，它將飛進地球低軌道，搜捕大件垃圾，然後在回航時，在大氣層中與垃圾玉石俱焚。

瑞士洛桑聯邦理工學院（EPFL）瑞士太空中心研發的「清潔太空一號」（CleanSpace One）衛星，長、闊、高分別僅為30厘米、10厘米、10厘米，像鞋盒般的骰。它會先飛到離地面630至750公里高的地球低軌道，追捕飛行時速高達2.8萬公里的太空垃圾，之後會伸出巨爪抓牢垃圾，最後與之進入地球大氣層中一起燒掉。每個「清潔太空一號」造價達1100萬美元（約8529萬港元），目前只能一次性使用，且無法抓捕細小垃圾。

抓垃圾進大氣層 一同燒毀

目前估計有約50萬件、總重量逾6000噸的報廢火箭碎片、衛星殘骸及塵粒等垃圾，正以快過子彈的高速不斷環繞地球旋轉，當中大部分垃圾都不逾1厘米大小。美國太空總署說，即使只跟細微垃圾撞擊都會產生巨大能量，可能損毀 衛星或宇航工具，威脅衛星效能甚至引發爆炸，危及太空人並產生更多太空垃圾。

儘管清理低軌道大件垃圾是個好開始，惟現行國際太空法規定，別國不能擅自清理他國造成的太空垃圾。「清潔太空一號」最快於2016年進行的首次任務，也只能抓回兩顆瑞士報廢衛星。（新科學家/福布斯）

嚴寒

Cold weather attracts skaters to frozen fens - in pictures

Visitors to the Fenlands in eastern England take advantage of sub-zero temperatures to enjoy skating on the frozen fens. Some areas of the region have seen temperatures plunge to as low as -18C in recent days

The sun rises over a frost-covered scene in in Earith, Cambridgeshire

Plants are covered in frost in Earith

A spider's web is covered in frost in sub-zero temperatures in Huntingdon, Cambridgeshire

2012年2月12日 星期日

冰封多瑙河 中歐5國停航

【明報】歐洲第2長河、橫跨10國的多瑙河在嚴寒天氣下多處結冰，奧地利、克羅地亞、塞爾維亞、保加利亞和匈牙利等國為安全起見停航，大大打擊中歐航運。

奧地利、匈牙利、克羅地亞、塞爾維亞及保加利亞境內有數十公里的多瑙河被冰封，癱瘓區內航運。塞爾維亞境內有588公里的多瑙河遭全面冰封，冰層厚達50厘米，情况是25年以來最嚴峻。塞爾維亞當局周五決定暫不以炸藥炸開冰封河面，令至少10天後才能恢復航運。匈牙利周四至周五因多瑙河冰層太厚而勒令停航，匈牙利軍隊已派遣旗下最大的破冰船到首都布達佩斯協助破冰。破冰船船長科瓦奇（Dezso Kovacs）指：「自1985年以來，我沒有見到多瑙河有這麼多冰。」

烏克蘭棄公布氣溫

除匈牙利外，奧地利、克羅地亞、塞爾維亞和保加利亞亦已叫停多瑙河航運。多瑙河由德國起途經歐洲10國至黑海，是全球經過國家最多的河流，亦是中歐各國的運輸、能源、水利、工業和漁業命脈。

今冬歐洲嚴寒已導致超過540人死亡。烏克蘭的氣溫持續低於-30℃，至今導致135人死亡，當局已放棄每天公布確實氣溫。羅馬尼亞則錄得4米積雪，民眾出入需經窗戶爬出或挖隧道。意大利首都羅馬則續刮風雪，積雪逾30厘米，學校停課，當局派出剷雪車和派發1000噸食鹽防止路面結冰。 （法新社）

Glacier thief arrested in Chile

Police hold man on suspicion of stealing five tonnes of ice from a glacier in Patagonia to sell as designer ice cubes for cocktails

A chunk of the 5,200kg of ice, believed stolen from the Jorge Montt glacier, which was discovered by police in a refrigerated truck.

Climate change sceptics have acquired a new explanation for why glaciersare retreating: it's not global warming, it's theft.

Police in Chile have arrested a man on suspicion of stealing five tonnes of ice from the Jorge Montt glacier in the Patagonia region to sell as designer ice cubes in bars and restaurants.

Local media reported that last Friday police intercepted a refrigerated truckwith an estimated £3,900 worth of illicit ice allegedly bound for whiskies, rums and cocktails in the capital Santiago...

snow

Temperatures plunge in Europe – in pictures

The death toll is rising in the cold snap across eastern Europe, with emergency crews working overtime as temperatures sink to -32C in some areas. Parts of the Black Sea froze along the Romanian coast and snow fell on Croatian islands in the Adriatic Sea. In Bulgaria, 16 towns recorded their lowest temperatures since records began. Western countries including France and Germany have also been affected

Think it's cold HERE? Beautiful pictures from around the globe show the whole world is freezing

Big freeze: A child runs past a wave protection dam covered in ice as the waters of the Black Sea are frozen near the shore in Constanta, Romania

Pillars of ice: Elegant icicles cover a protective fence beside the waters of the Black Sea

Cold creatures: Amateur photographers capture the ice on a dam beside the shore, as a gull flies over the splendid landscape

a solitary figure heads along the Neris river in the Vilnius, Lithuania

Beautiful: A duck stretches its wings over a steamy pond on the outskirts of Minsk, Belarus

Christmas train: A narrow-gauge railway makes its way through a snow covered forest at the Harz national park near Schierke, central Germany

Spectacular sunrise: Ice floes float down the German-Polish border river Oder during sunrise near Frankfurt Oder, Germany