But Paul Hodge, an astronomer at the University of Washington, thinks this new graphic is an improvement over older, Earth-bound observations. Scientists have known about changing star patterns since astronomer Edmond Halley first wrote about proper motion in 1718, and portrayals of these changes have been published for a long time. The further away a set of stars are, the less their configuration will appear to change from our perspective-even on the scale of 100,000 years. Compared to the stars of Orion's Belt (above), which are about 1,000 light-years away, the Dipper's shape will change relatively quickly. Why does Sirius twinkle and change colors while Mars does not? Check out Phil Plait’s explanation on his Bad Astronomy site.The Big Dipper, for example, is made up of stars that are about 100 light-years away from Earth. Unlike Sirius Mars does not appear to twinkle and is a constant red beacon in the East. At the time its brightness almost matched that of Sirius. Last month Mars was at its closest and brightest for the year. The final “star” in the line is the red planet Mars. Procyon‘s name derives from its slightly more northerly declination which causes it to rise a few minutes before Sirius (at least for northern observers). In this case, the “Dog” is Sirius which has long been associated with a dog. The name Procyon comes from Greek and means “before the Dog”. It is also less massive (1.5 times solar mass) but a bit larger (2 times solar radius) than Sirius. Procyon appears fainter than Sirius because it is intrinsically fainter (7.7 times brighter than the Sun versus 25 times brighter for Sirius) and farther away (11.4 light years vs. Next in line is white Procyon, the seventh brightest star in the sky at magnitude 0.3. Watching Sirius when low in the sky with a telescope or just your eyes can be one of the best sights in the night sky. All stars experience this effect, it is just that Sirius‘ brightness makes it more evident. As a result, normally blue Sirius can appear to rapidly switch between many different colors when it is close to the horizon (meaning its light is passing through more atmosphere than usual). ![]() The light of the star is made up of many different colors which all “bounce” around differently. Turbulence in the atmosphere causes the star’s light to be “bounced” all over the place. The reason for this is due to the Earth‘s atmosphere. Many times, though, the star will appear to rapidly change color. Sirius is an A-type star which causes it to shine with a white-blue color. At a distance of 8.6 light years, it is the 5th closest stellar system. ![]() The reason for its status as the brightest star in the sky is due more to its relatively close distance than its luminosity. Still there are many stars in the sky that are even larger and more luminous than Sirius. ![]() ![]() Relative to the Sun, Sirius is twice as massive, has a radius 70% larger, and is 25 times more luminous. Only the Moon, Venus, Jupiter, and occasionally Mars are brighter. Not only is Sirius the brightest of the three (at magnitude -1.5), it is the brightest star in the entire night sky. Let’s start with the Sirius, the southernmost and brightest of the three. The 3 “stars” are, in fact, 2 stars and a planet: Sirius, Procyon, and Mars. The star Procyon is located between Mars and Sirius. View of the East-Southeast sky in the early evening. About a third of the way from the horizon to the zenith (straight up), 3 bright “stars” can be seen spread out from due East to the South-South-East (see the chart below). When it is dark enough to see a few stars in the sky during evening twilight, look to the East and Southeast.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |