Waltz of the Planet and Its Moons

Cassini mendekati Saturnus (Wikipedia)

Cassini, sebuah wahana ruang angkasa tanpa awak yang dikirimkan untuk mengamati planet bercincin Saturnus, telah memberikan gambar-gambar planet tersebut yang belum pernah dilihat sebelumnya. Diluncurkan tahun 1997, wahana ini sampai di sistem planet Saturnus pada tahun 2004 dan terus mengirim gambar-gambar ekskulsif tentang planet yang memiliki cincin yang menakjubkan ini.

Gambar-gambar tersebut dirangkai dalam bentuk video oleh Fabio di Donato dan diiringi dengan musik latar The Second Waltz dari Dmitri Shostakovich menjadi tontonan yang menarik.

Silakan nikmati tayangan video yang ada dalam artikel ini: 

http://www.slate.com/blogs/bad_astronomy/2013/07/27/_around_saturn_a_time_lapse_video_made_from_cassini_images_of_the_ringed.html?wpisrc=most_viral

atau disini:

https://www.youtube.com/watch?v=VnyuQjegeFk
Selamat berdansa bersama Saturnus dan beberapa bulannya, diantaranya Prometheus, Iapetus, Helena dan Hyperion.

Eksoplanet Deep Blue Dot, planet yang eksotis

Gambaran artis untuk HD 189733b, gas biru raksasa (Sky & Telescope)

Para astronom yang tergabung dalam tim astronom internasional baru-baru ini menemukan eksoplanet (planet yang mengelilingi sebuah matahari, mirip dengan bumi), yang berwarna kebiruan. 

Tapi jangan kemasi dulu barang anda untuk ikut dalam misi penerbangan kesana, karena eksoplanet yang diberi nama Deep Blue Dot itu (HD 189733b) ternyata adalah sebuah bola gas raksasa, yang letaknya terlalu dekat dengan bintangnya, dengan suhu permukaan 1200 derajat Celsius. 

Planet yang jaraknya terhadap bintangnya sepuluh kali lebih dekat dari Merkurius ke matahari ini ternyata sama sekali bukan tempat yang nyaman untuk dikunjungi. Teleskop ruang angkasa Hubble telah mencoba mengukur cahaya yang keluar dari planet ini dan warna yang muncul adalah biru tua. 

Bola gas raksasa biru yang menarik itu disamping sangat panas, juga memiliki hujan gelas yang berjatuhan dengan kecepatan 15 ribu kilometer per jam. Para ahli memperkirakan penyebab warna biru tua itu disebabkan oleh partikel silikat yang bertebaran di atas permukaan planet, berupa butiran-butiran gelas yang memantulkan warna biru. 

Jadi, permukaan planet ini jauh lebih "parah" dari permukaan planet Jupiter dimana pemukaannya tertutup awan amonia. Planet Uranus dan Neptunus juga berwarna kebiruan, tapi ini karena kandungan metan yang ada di atmosfirnya menyerap warna merah. 

Eksoplanet ini menambah daftar jumlah eksoplanet yang sudah ditemukan selama ini, dan yang paling banyak diteliti. Pertama karena ukurannya yang besar, hampir menutupi bintang yang dikitarinya, yang terletak di rasi Vulpecula, yang jauhnya "hanya" 63 tahun cahaya dari kita, juga karena warnanya yang eksotis, biru tua, mirip dengan warna bumi kita. (Disarikan dari tulisan Mark Zatrow dalam Sky & Telescope). 

The twilight and the full moon...

The twilight and the full moon as observed from my backyard...

    As observed from my backyard in my house in Purwakarta

    As observed from my deck in my house in Jakarta

I swear by the evening twilight,
I swear by the night and everything shrouded it,
I swear by the full moon,
That you will climb from stage to stage (in life).....
(Sura 84, verses 16-19)

Selection from the Holy Qur'an, rendered into simple English, O.P. Ghai as quoted by my colleague Sri Hadiarti in FB, 2 July 2013, in welcoming the holy month of Ramadan, May God bless us and give us strength and patience.

Pleiades and its local folklore

I guess there are no other deep sky objects that attract people most as Pleiades (M45). Any folklore has at least a version that tells a story about seven sisters, or seven goddess or fairies (bidadari in Indonesian) as the Javanese called. Pleiades is relatively easy to locate. Even with an unaided eye, this object could be seen as dots of tiny stars in the dark sites in the constellation Taurus, the Bull. I saw Pleiades for the first time on July 13, 2008 from my backyard in Purwakarta. With binocular, these seven stars could be seen clearly as cluster of tiny stars. 

Although it consists of hundreds of stars, Pleiades is known for its seven brilliant stars, commonly visible to unaided eyes. The name of each star comes from Greek mythology, these are Electra, Taygeta, Maia, Asterope, Alcyone, Merope and Alcyone. My colleague Purwanto Nugroho of ISG has been able to capture this beautiful object. He is a talented person with many skills, photography, playing saxophone, diving. He is also very good in taking astrophotography. Here is his photo of Pleiades he took on August 18, 2012:

Pleaides, the Seven Sisters, photo by Purwanto Nugroho

Pleiades is so famous that it is reflected in many folklores that go with various stories, including from Indonesia. In our language, Pleiades is known as ‘Kartika’. The story tells that seven fairies from heaven were taking bath in a river, where Jaka Tarub, a local handsome man was bewitched with the beauty of these fairies. He silently stole one of the fairy’s scarf. While the rest of the fairies went back to heaven, Nawangwulan, the one left behind, could not fly back home because she could not find her scarf. Then Jaka Tarub asked Nawangwulan to marry him. They finally married and had one daughter, Dewi Nawangsih. But one day, as she discovered her scarf and learned that it was in fact stolen by Jaka Tarub, she got angry and wanted to return to heaven, although her husband begged her not to leave him. She insisted, but promised that she will be back one in a time to breast feed her daughter. 

If you once noticed that one of the Pleiades’ stars disappeared, it probably is Nawangwulan who is feeding her lovely daughter. This legend inspired Basuki Abdullah, one of Indonesian prominent painters, to produce the famous painting on “Jaka Tarub and Seven Fairies” or “Jaka Tarub dan Tujuh Bidadari”, which was later followed by many other painters in various styles. Basuki Abdullah is one of Soekarno’s favorite painters. Many of his paintings become Soekarno’s collection. See his painting on “Jaka Tarub and Seven Fairies” in the following link: http://asian-paintings.blogspot.com/2009/04/art-of-basuki-abdullah.html

Omega Centauri, a vast globuar cluster

Omega Centauri (NGC5139) is a deep sky object in the southern sky region. With the naked eye, this object is almost like another ordinary star, but it has millions of stars packed together. Omega Centauri could easily be located by taking a straight line beyond stars Hadar and Eta Centauri, and a straight line beyond Acrux and Mimosa. The intersection of these two lines is where NGC5139 is (see sketch below).

I was able to capture Omega Centauri on June 16, 2010 from my backyard in Purwakarta with my Nikon D90. I will someday take a closer look and capture this object with my C6, and present the photo in this blog. God permitting! 

With its distance of 16,000 light years, and yet still visible, one could imagine the vastness of this object. Its mass is equivalent to five million suns and ten times more massive as compared to other large clusters. Within the local group, its brightness is only comparable to Andromeda galaxy, M31.  

This object was first discovered by Edmond Halley in 1677. Observation on the center of Omega Centauri by Astronomical Institutes of the University of Bonn revealed that this object consists of millions of giant red and blue stars, and dwarf gray stars. The diameter of this cluster is about 150 light years, and when we look at moonless clear night, its diameter is almost the same as the moon. This is one of the oldest stars in the universe, with 16 billion years of age.     

Omega Centauri (NGC5439), photo by Anglo-Australian Observatory

Omega Centauri in the southern sky region, photo by me taken from my backyard in Purwakarta

Hunting for Messier objects

110 Messier objects over night? No kidding!

Charles Messier (26 June 1730 – 12 April 1817) was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters and that came to be known as the 110 "Messier objects" (Wikipedia). 

M7 is the first DSO under Messier list I had successfully “discovered”. In May 2008, I was trying to “discover” another Messier objects. I have read an article on how an amateur astronomer had been able to locate ALL 110 Messier objects over one night! (Read Inside a Messier Marathon by Art Fritzson - http://www.cloudynights.com/item.php?item_id=1446). This could have been very exhaustive observing activity ever done. Well, I don’t think I could do the same, but, why not trying…

In May 2008 I started my hunting for Messier objects in Sagittarius. The “teapot” is a nickname for constellation Sagittarius, as the main portion of the constellation resembles a teapot. One of the stars that forms the “teapot” cover is Kaus Borealis (Lambda Sagitarii), and M22 (NGC6656) is located near this star. I was able to locate this DSO for the first time on the night of May 25. 

With its magnitude of only 5.1, M22 is not easy to find. One way to see this low magnitude object is by the “averted vision” method, where our eyes are not seeing the object directly. M22 was seen as a hazy cotton-like object. No wonder, M22 is located about 10,400 light-year. The question that came to my mind, is this object still exist at this point of time?  About 5 degrees to the left is another fuzzy object: M25 (IC4725). I was lucky enough that night that I was also able to locate M6 (NGC6405 or known as Butterfly cluster). I could not find this object the other night. M6 is located near the famous M7, but with its magnitude of 4.2, this DSO is so difficult to locate. Still long way to complete all 110 objects, but it will be really fun, I guess. I only pray for a clear sky every night.

Capturing these DSOs with camera is another challenge, especially for those with very low magnitude. I still need to practice my skill in astro--photography, but some day I promise I will show these in this blog, God permitting!

Observing deep sky objects

How ”deep” is a deep sky object?

 

M7 (NGC 6475) as seen in the eyepiece of my C6 NGT, taken with Nikon D90 for a few minutes exposure

M7 (NGC6475) is the first deep sky object (DSO) that I could observe with my C6. It was in April 2008 when I noticed a crowd of tiny stars filling in the eyepiece between Shaula (in Scorpius) and Kaus Australis (in Sagittarius). M7 was already spotted by Ptolemeus in around 130 BC, but the first serious observation of this object was done by Hodiernes in 1654, and he counted 30 stars in the crowd.  Messier listed this object as number 7 in his list on May 23, 1764, and I could only see this object with my own eyes 244 years later. M7 is located about 800 light years. This means I had just seen a light from year 1200s! M7 remains my favorite DSO object until now.

The night sky in May 2008 was exceptionally clear. Before dawn, I scanned again the tail region of Scorpius towards Sagittarius. This is a DSO-rich region, the center of the Milky Way. On the “right’ side of M7, I noted two crowds which I believed were M8 (NGC6523 also known as Lagoon Nebula) and M20 (NGC6514 known as Trifid Nebula). Both DSOs are famous for their beautiful colors, which could be seen on long-exposure shots.    

I learned from Stellarium (www.stellarium.org), that M20 has its neigbor: M21 (NGC6531). M21, together with M20, was first noticed by Messier in 1794. Its distance from us is around 3,000 light years. That night, I saw the light from M21 touched my retina from year 1,000 BC!