উইকিশৈশব:সৌরজগৎ/নেপচুন

Neptune as seen from Voyager 2

Neptune symbol (bold, blue).svgনেপচুন হচ্ছে সৌরজগতের অষ্টম গ্রহ। অর্থাৎ, সূর্য থেকে দূরত্বের ভিত্তিতে পূর্ণাঙ্গ গ্রহের মর্যাদা পাওয়া আটটি গ্রহের মধ্যে এটিই সর্বশেষ গ্রহ। এটি একটি গ্যাসীয় দানব। অর্থাৎ, সৌরজগতের প্রথম চারটি গ্রহে থাকা পাথুরে পৃষ্ঠের মতো কোনো পৃষ্ঠ এই গ্রহে নেই।

Neptune symbol.svg Neptune Facts:
  • Wind speeds on Neptune can reach 450 meters per second.
  • Neptune was discovered because its gravitational field was affecting the orbit of Uranus.
  • Neptune is sometimes farther from the Sun than Pluto.

How big is this planet ?সম্পাদনা

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নেপচুন ও পৃথিবীর আকারের তুলনা

আকারে দিক থেকে নেপচুন তার পূর্বের গ্রহ ইউরেনাসের সাথে বেশ সাদৃশ্যপূর্ণ। তবে নেপচুনের ব্যাস সামান্য ছোট। গ্রহটি ৪৯,৫২৮ কিলোমিটার চওড়া।[১] এটি দৈর্ঘ্যে প্রায় চারটি পৃথিবীর মতো বড়।[২]

What is its surface like?সম্পাদনা

নেপচুনের বায়ুমণ্ডলে কিছু গাঢ় নীল ছোপ রয়েছে। ১৯৮৯ সালে যখন ভয়েজার প্রোব নেপচুনের কাছে যায়, তখন এটি গ্রেট ডার্ক স্পট নামে একটি বড় ছোপ দেখেছিল। ১৯৯৪ সালে এটি অদৃশ্য হয়ে যায়, কিন্তু পরে পুনরায় আবির্ভূত হয়।[৩] এছাড়াও ইউরেনাসে একটি বড় সাদা মেঘ রয়েছে। এর ডাকনাম "স্কুটার"। এটি প্রতি ১৬ ঘন্টায় নেপচুনের চারপাশে আবর্তন করে।[৪] নেপচুনের বাতাসের বেগ খুব বেশি। এর বাতাস ঘন্টায় ২০০০ কিমি পর্যন্ত প্রবাহিত হতে পারে। তাই সৌরজগতে নেপচুনের বায়ুপ্রবাহই দ্রুততম।[৫] এই গতি পৃথিবীর দ্রুততম রেকর্ড করা টর্নেডোর চেয়ে প্রায় চার গুণ দ্রুত।

What are its rings like?সম্পাদনা

Neptune has some faint rings that are dark and hard to see. There are clumps in some parts of the rings where the material is denser.[৬]

What are its moons like?সম্পাদনা

Neptune has 13 moons. There could be more.[৭]

Inner Moonsসম্পাদনা

There are five small potato-shaped moons orbiting close to Neptune.

Proteusসম্পাদনা

Proteus is a dark moon about 418 km across. It has an irregular shape. In Roman mythology Proteus was a sea-god who could change into any shape he wanted.[৮]

Tritonসম্পাদনা

Triton is the largest moon of Neptune. Scientists think that it is a lot like Pluto. It is 2700 km across. It is made of rock and ice. It has a surface temperature of −235 °C Triton has a very thin atmosphere made up of nitrogen and a little methane.

There are volcanoes that have eruptions of liquid nitrogen, dust or methane compounds. The eruptions happen because of the seasons. There are few craters because the eruptions cover them up. There are ice caps that change sizes with the seasons. There are also ridges and valleys. They may have formed because of repeated freezing and thawing.

An interesting thing about Triton's orbit is that it goes around Neptune in the opposite direction that Neptune's rotates. Because of this, scientists think that Triton was captured by Neptune long ago. In Roman mythology, Triton was the son of Neptune.[৯]

Nereidসম্পাদনা

Nereid is an irregularly shaped moon about 340 km across. Its orbit is very eccentric or noncircular. It may have been captured by Neptune or moved into the eccentric orbit by Triton's gravity when Triton got captured. In Roman mythology Nereids were sea nymphs.[১০]

Outer Moonsসম্পাদনা

There are five other known moons. They are small potato-shaped moons far from Neptune. There might be more we haven't seen yet.

How long is a day on this planet?সম্পাদনা

A day on Neptune lasts 16 hours and 7 minutes.[১১]

How long is a year on this planet?সম্পাদনা

One year on Neptune is about 165 Earth years, or 60,265 days.[১২]

What is it made of?সম্পাদনা

Neptune is made of rock and metal in the core. The core is probably bigger than Uranus's because Neptune weighs more, but is the same size. Around the core is rock, water, ammonia and methane. The atmosphere is made of hydrogen and helium. Lower down in the atmosphere, there is methane and ammonia too. The methane makes Neptune look blue-green.[১৩]

 
Artistic impression of the mythological Neptune

How much would Neptune's gravity pull on me?সম্পাদনা

If you were floating close to the cloud tops of Neptune, it would pull you down with a force only a little stronger than the force of Earth's gravity.[১৪] The effects of Neptune's larger radius and its mass almost cancel out, making the force only a little bigger.

Who is it named after?সম্পাদনা

Neptune is named after the Roman god of the seas, also known as Poseidon in ancient Greece. [১৫]

Next Topic: Pluto

Referencesসম্পাদনা

  1. Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  2. http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html
  3. Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  4. http://www.nineplanets.org/neptune.html; http://www.moreheadplanetarium.org/index.cfm?fuseaction=page&filename=science_resources_neptune.html
  5. http://www.nineplanets.org/neptune.html; http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level1/neptune.html
  6. Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  7. http://www.nineplanets.org/neptune.html
  8. http://www.nineplanets.org/proteus.html
  9. http://www.nineplanets.org/triton.html
  10. http://www.nineplanets.org/nereid.html
  11. Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  12. http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html; Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  13. http://www.nineplanets.org/neptune.html; Smith, Bradford A. "Neptune." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar386900; http://www.nasa.gov/worldbook/neptune_worldbook.html
  14. Snow, Theodore P. (1996) "The Outer Planets." In The Dynamic Universe: An Introduction to Astronomy. pp. 281. West Publishing Company. আইএসবিএন 0-314-64212-9
  15. Snow, Theodore P. (1996) "The Outer Planets." In The Dynamic Universe: An Introduction to Astronomy. pp. 282. West Publishing Company. আইএসবিএন 0-314-64212-9