How the sun will die : and what happens to earth?

Dark Matter Structure Revealed

The Dark Matter & Dark Energy [1/5]

Dark Matter

Dark Matter

When the Universe was young, it was nearly smooth and featureless. As it grew older and developed, it became organized. We know that our solar system is organized into planets (including the Earth!) orbiting around the Sun. On a scale much larger than the solar system (about 100 million times larger!), stars collect themselves into galaxies. Our Sun is an average star in an average galaxy called the Milky Way. The Milky Way contains about 100 billion stars. Yes, that's 100,000,000,000 stars! On still larger scales, individual galaxies are concentrated into groups, or what astronomers call clusters of galaxies.

 

An overlay of an optical image of a cluster of galaxies
with an x-ray image of hot gas lying within the cluster

The cluster includes the galaxies and any material which is in the space between the galaxies. The force, or glue, that holds the cluster together is gravity -- the mutual attraction of everything in the Universe for everything else. The space between galaxies in clusters is filled with a hot gas. In fact, the gas is so hot (tens of millions of degrees!) that it shines in X-rays instead of visible light. In the image above, the hot X-ray gas (shown in pink) lying between the galaxies is superimposed on an an optical picture of the cluster of galaxies. By studying the distribution and temperature of the hot gas we can measure how much it is being squeezed by the force of gravity from all the material in the cluster. This allows scientists to determine how much total material (matter) there is in that part of space.

Remarkably, it turns out there is five times more material in clusters of galaxies than we would expect from the galaxies and hot gas we can see. Most of the stuff in clusters of galaxies is invisible and, since these are the largest structures in the Universe held together by gravity, scientists then conclude that most of the matter in the entire Universe is invisible. This invisible stuff is called 'dark matter', a term initially coined by Fritz Zwicky who discovered evidence for missing mass in galaxies in the 1930s. There is currently much ongoing research by scientists attempting to discover exactly what this dark matter is, how much there is, and what effect it may have on the future of the Universe as a whole.

The Black Hole

The Black Hole

Despite its invisible interior, the presence of a black hole can be inferred through its interaction with other matter and with light and other electromagnetic radiation. Matter falling onto a black hole can form an accretion disk heated by friction, forming some of the brightest objects in the universe. If there are other stars orbiting a black hole, their orbit can be used to determine its mass and location. These data can be used to exclude possible alternatives (such as neutron stars). In this way, astronomers have identified numerous stellar black hole candidates in binary systems, and established that the core of our Milky Way galaxy contains a supermassive black hole of about 4.3 million solar masses.

A black hole is a region of spacetime where gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[2][3] Quantum mechanics predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater.

Objects whose gravity field is too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was not fully appreciated for another four decades. Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies.

Penciptaan Alam Semesta

4 Puspa Langka di Bengkulu Pemecah Rekor Dunia

BUNGA RAFLESIA

Bunga Raflesia

Bunga Raflesia

Rafflesia adalah genus tumbuhan bunga parasit. Ia ditemukan di hutan hujan Indonesia oleh seorang pemandu dari Indonesia yang bekerja untuk Dr. Joseph Arnold tahun 1818, dan dinamai berdasarkan nama Thomas Stamford Raffles, pemimpin ekspedisi itu. Ia terdiri atas kira-kira 27 spesies (termasuk empat yang belum sepenuhnya diketahui cirinya seperti yang dikenali oleh Meijer 1997), semua spesiesnya ditemukan di Asia Tenggara, di semenanjung Malaya, Kalimantan, Sumatra, dan Filipina. Tumbuhan ini tidak memiliki batang, daun ataupun akar yang sesungguhnya. Rafflesia merupakan endoparasit pada tumbuhan merambat dari genus Tetrastigma (famili Vitaceae), menyebarkan haustoriumnya yang mirip akar di dalam jaringan tumbuhan merambat itu. Satu-satunya bagian tumbuhan Rafflesia yang dapat dilihat di luar tumbuhan inangnya adalah bunga bermahkota lima. Pada beberapa spesies, seperti Rafflesia arnoldii, diameter bunganya mungkin lebih dari 100 cm, dan beratnya hingga 10 kg. Bahkan spesies terkecil, Rafflesia manillana, bunganya berdiameter 20 cm. Bunganya tampak dan berbau seperti daging yang membusuk, karena itulah ia disebut "bunga bangkai" atau "bunga daging". Bau bunganya yang tidak enak menarik serangga seperti lalat dan kumbang kotoran, yang membawa serbuk sari dari bunga jantan ke bunga betina. Sedikit yang diketahui mengenai penyebaran bijinya. Namun, tupai dan mamalia hutan lainnya ternyata memakan buahnya dan menyebarkan biji-bijinya. Rafflesia adalah bunga resmi negara Indonesia, begitu pula provinsi Surat Thani, Thailand.

Nama "bunga bangkai" yang dipakai untuk Rafflesia membingungkan karena nama umum ini juga digunakan untuk menyebut Amorphophallus titanum (suweg raksasa/batang krebuit) dari famili Araceae. Terlebih lagi, karena Amorphophallus mempunyai perbungaan tak bercabang terbesar di dunia, ia kadang-kadang secara salah kaprah dianggap sebagai bunga terbesar di dunia. Baik Rafflesia maupun Amorphophallus adalah tumbuhan bunga, namun hubungan kekerabatan mereka jauh. Rafflesia arnoldii mempunyai bunga tunggal terbesar di dunia dari seluruh tumbuhan berbunga, setidaknya bila orang menilai dari beratnya. Amorphophallus titanum mempunyai perbungaan tak bercabang terbesar, sementara palem Talipot (Corypha umbraculifera) memiliki perbungaan bercabang terbesar, terdiri atas ribuan bunga; tumbuhan ini monokarpik, yang artinya tiap individu mati setelah berbunga.