黑色皮革手册

水上“大圆桌”亮相湘湖克鲁兹王莲迎来最佳观赏期_我的网站

一 | “简直就像一个个大圆桌”“第一次见到这种植物，是什么品种？”“它会开花吗？”……这两天，不少市民惊喜地发现湘湖“十里荷香”迎来新变化——一张张巨大的绿色莲叶漂浮于水面，叶片舒展，为湖畔增添了别样韵味。记者从湘湖管委会了解到，这是新晋落户的克鲁兹王莲。今年6月，湘湖首次引种40株克鲁兹王莲，历经夏日滋养，在处暑节气悄然成形。图片来源：湘湖管委会不同于普通荷叶的纤细灵动，王莲自带大气磅礴的姿态，成熟叶片直径可达1.5至2米，硕大的翠叶平整舒展浮于碧波之上，叶缘整齐上翘，宛如一方方天然青玉圆桌，错落点缀在湖面，层层叠叠，绿意盎然，为渐入清秋的湘湖留住了满目生机。 Washington, Oct 12 (UNI) American space agency NASA says its recent attempt to deflect the path of an asteroid was successful, after its Dart probe struck an asteroid head-on.
Scientists have now confirmed the orbit of a 160m-wide space rock known as Dimorphos was altered when the Dart probe struck it head on last month.
Researchers came to the conclusion after making measurements using a range of space and Earth-based telescopes.
The mission was conceived to test a potential strategy to defend the Earth against threatening objects.
Dart's achievement proves such an idea would work, provided it was initiated early enough and the target wasn't overly massive.
"This mission shows that Nasa is trying to be ready for whatever the Universe throws at us," said agency administrator Bill Nelson.
"I believe that Nasa has proven that we are serious as a defender of the planet," he told reporters.
The space agency released a raft of data on Tuesday to support its assessment, including new pictures from the Hubble Space Telescope and from a small Italian spacecraft that stood off from the impact by about 50km (30 miles).
The Double Asteroid Redirection Test (Dart) took place some 11 million km (7 million miles) from Earth.
It saw the refrigerator-sized Nasa satellite drive straight into Dimorphos at 22,000km/h (14,000mph), destroying itself in the process.
The space rock orbits a much larger (780m wide; 2,550ft) object called Didymos. Before impact, the time taken for Dimorphos to make one circuit of its sibling was 11 hours and 55 minutes.
The telescope evidence now indicates this orbital period has been reduced to 11 hours and 23 minutes - a change of 32 minutes. This corresponds to Dimorphos moving closer into to Didymos by "tens of metres".
Nasa had defined a minimum successful period change of Dimorphos of 73 seconds or more. The results released on Tuesday show Dart surpassed this benchmark by more than 25 times.
"This is a 4 percent change in the orbital period of Dimorphos around Didymos. Dart just gave it a small nudge. But if you wanted to do this in the future, you'd want to do it years in advance," commented Nancy Chabot from the Johns Hopkins University Applied Physics Laboratory, which led the mission for Nasa.
"Warning time is really key here in order to enable this sort of asteroid deflection to be used in the future as part of a much larger planetary defence strategy."
Nasa's Dart programme scientist, Tom Statler, also had a word of caution about drawing too many conclusions from the experiment.
Asteroids came in many different guises, he said. Their compositions and constructions were diverse - something that was being emphasised every time a mission visited a new object.
"We should not be too eager to say one test on one asteroid tells us exactly how every other asteroid would behave in a similar situation," he stressed.
"But what we can do is use this test as an anchor point for our physics calculations in our simulations that tell us how different kinds of impacts in different situations should behave."
Four years from now, the European Space Agency (Esa) will have three spacecraft - collectively known as the Hera mission - at Didymos and Dimorphos to make follow-up studies.
UNI ING。如果走近了仔细观察这一方方“水上玉盘”，还会发现许多暗藏着自然的精巧玄机。王莲叶背布满粗壮的网状叶脉与细密尖刺，独特的气室结构赋予它超强浮力，均匀承重下可承载数十公斤重量。

二 | 对于王莲有一定了解的市民，或许曾经看到过这样的图片：游客坐在巨大的莲叶上打卡留念。

三 | 未来，湘湖是否也会有类似的活动？湘湖管委会工作人员透露，今年是初次种植，目前叶面大小还未达到能支撑人体重量的程度。“大家还得再等等，等王莲的直径和承重能力达标后，我们也会考虑推出人上王莲打卡的服务。”再来说说王莲花，作为独特的“夜开型”花卉，王莲花仅有三日花期，却日日换新颜，第一夜初开时为纯白色，第二晚转为粉红色，第三日变为紫红色，之后闭合沉入水中结实。