How Do We Calculate Distances of This Magnitude?Ĭepheid Variable stars are used to calculate distances of this magnitude. This translates to 2.3 million light years, or 725 kpc. When we talk about the distances to other galaxies, we often use the units of kiloparsec (kpc) and Megaparsec (Mpc). It is also possible that the Local Group may one day merge with the next nearest big galaxy cluster, the Virgo Cluster. The dynamics of the Local Group are changing, and some astronomers speculated that one day the two large spirals in it (M31 and the Milky Way) may collide and merge to form a giant elliptical galaxy. Both M31 and the Milky Way have dwarf galaxies associated with them. M31 and the Milky Way are the most massive members of the Local Group, with M33 being the 3rd largest. There are over 30 galaxies that are considered to be in the local group, and they are spread over a diameter of nearly 10 million light years, with the center of them being somewhere between the Milky Way and M31. It has two small satellite galaxies, M32 and M110.Īlso prominent in the local group is the Triangulum Galaxy (M33), Leo I, and NGC 6822. If you do not have Redshift - no problem you can download the free Launcher here.One of the most prominent members of the Local group is M31, the Andromeda Galaxy. Open it with Redshift 7 and explore that region of space yourself. Redshift live created a workspace showing Enceladus and Saturn. The active area around Enceladus's south pole is about 10 percent of its surface. Their model suggests the active periods have occurred only 1 to 10 percent of the time that Enceladus has existed and have recycled 10 to 40 percent of the surface. The model fits the activity on Enceladus when the churning and resurfacing periods are assumed to last about 10 million years, and the quiet periods, when the surface ice is undisturbed, last about 100 million to two billion years. Nimmo said the bubbles are probably just below freezing, which is 273 degrees Kelvin or 32 degrees Farenheit, whereas the surface is a frigid 80 degrees Kelvin or -316 degrees Fahrenheit.) The rise of the warm bubbles would send cold, heavier ice down into the interior. The south polar area, however, appears to be less than 100 million years old, possibly as young as 500,000 years.Ī new model showed that heat building up from the interior of Enceladus could be released in episodic bubbles of warm, light ice rising to the surface, akin to the rising blobs of heated wax in a lava lamp. Heavily cratered plains in the northern part of the moon appear to be as old as 4.2 billion years, while a region near the equator known as Sarandib Planitia is between 170 million and 3.7 billion years old. The surface ages of different regions of Enceladus also show great diversity. Tidal movement – the pull and push from Saturn as Enceladus moves around the planet – cannot explain the release of so much energy. The region was also later found by Cassini's ion and neutral mass spectrometer instrument to be swiftly expelling argon, which comes from rocks decaying radioactively and has a well-known rate of decay.Ĭalculations told scientists it would be impossible for Enceladus to have continually produced heat and gas at this rate. ![]() ![]() This is at least three times as much heat as an average region of Earth of similar area would produce, despite Enceladus' small size. "Why is the south polar surface so young? How could this amount of heat be pumped out at the moon's south pole? This idea assembles the pieces of the puzzle."Ībout four years ago, Cassini's composite infrared spectrometer instrument detected a heat flow in the south polar region of at least 6 gigawatts, the equivalent of at least a dozen electric power plants. "This episodic model helps to solve one of the most perplexing mysteries of Enceladus," said Bob Pappalardo of the research done by his colleagues. 10, doesn't link the churning and resurfacing directly to the formation of fissures and jets, it does fill in some of the blanks in the region's history. The south polar region captivates scientists because it hosts the fissures known as "tiger stripes" that spray water vapor and other particles out from the moon. "These tumultuous periods are rare and Cassini happens to have been watching the moon during one of these special epochs."
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