Why milky way is spiral

The Sun is located in a minor arm, or spur, named the Orion Spur. The galactic disk itself is about , light years across, and the bar at the center is estimated to be about 27, light years long. Why is the Milky Way a spiral? This is due to its rotation , or rather, the rotation of matter inside the galactic disk around the center. While some theories expect this swirl of stellar streams may have been born after another, smaller galaxy crashed into the Milky Way, others believe it came to existence naturally as a result of the rotation of the galactic disc.

The next batch of Gaia data, the full Data Release 3, is expected to be made available to scientists worldwide in about mid Gaia, one of the most productive missions in history measured by the number of scientific papers it produces , will continue scanning the sky until The vast catalogues of stellar positions, motions and velocities it creates will keep astronomers busy for decades to come.

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And if you have a news tip, correction or comment, let us know at: community space. Tereza is a London-based science and technology journalist, aspiring fiction writer and amateur gymnast. Originally from Prague, the Czech Republic, she spent the first seven years of her career working as a reporter, script-writer and presenter for various TV programmes of the Czech Public Service Television. She worked as a reporter at the Engineering and Technology magazine, freelanced for a range of publications including Live Science, Space.

Magnetic fields in the spiral galaxy are aligned with the spiral arms across the entire galaxy—more than 24, light years across. The magnetic field alignment with the star formation implies that the gravitational forces that created the galaxy's spiral shape is also compressing the magnetic field. The alignment supports the leading theory of how the arms are forced into their spiral shape known as "density wave theory. Scientists measured magnetic fields along the spiral arms of the galaxy called NGC , or M The fields are shown as streamlines that closely follow the circling arms.

The M77 galaxy is located 47 million light years away in the constellation Cetus. It has a supermassive active black hole at its center that is twice as massive as the black hole at the heart of our Milky Way galaxy. The swirling arms are filled with dust, gas and areas of intense star formation called starbursts. SOFIA's infrared observations reveal what human eyes cannot: magnetic fields that closely follow the newborn-star-filled spiral arms.

This supports the leading theory of how these arms are forced into their iconic shape known as "density wave theory. Instead, the material moves along the arms as gravity compresses it, like items on a conveyor belt.

The magnetic field alignment stretches across the entire length of the massive, arms—approximately 24, light years across. This implies that the gravitational forces that created the galaxy's spiral shape are also compressing its magnetic field, supporting the density wave theory. The results are published in the Astrophysical Journal. Celestial magnetic fields are notoriously difficult to observe.

From these results, astronomers can infer the shape and direction of the otherwise invisible magnetic field. Far-infrared light provides key information about magnetic fields because the signal is not contaminated by emission from other mechanisms, such as scattered visible light and radiation from high-energy particles. SOFIA's ability to study the galaxy with far infrared light , specifically at the 89 micron wavelength, revealed previously unknown facets of its magnetic fields.

Further observations such as these from SOFIA are necessary to understand how magnetic fields influence the formation and evolution of other types of galaxies, such as those with irregular shapes.

The scientists , Andrew Benson of the California Institute of Technology Caltech and Nick Devereux of Embry-Riddle University in Arizona, tracked the evolution of galaxies over thirteen billion years from the early universe to the present day. Galaxies are the collections of stars, planets, gas, and dust that make up most of the visible component of the cosmos. The smallest have a few million and the largest as many as a million million a trillion stars. There are three basic shapes:.

This figure illustrates the Hubble Sequence. On the left are elliptical galaxies, with their shapes ranging from spherical E0 to elongated E7. Type S0 is intermediate between elliptical and spiral galaxies.