In the news published on 27/2 (see below below) we promised a forecast for the inventions of two comets in the sky. Eran Ofek reminds us today that starting tomorrow we will be able to see one comet in the evening and one in the early morning
Comet HaleBopp, one of the brightest comets observed in recent years, visited our name in 1997. On the right - in a photo taken from Mitzpe Ramon and on the left a photo from abroad. If all the material could be collected in the tail of a comet, it would easily fit in a suitcase
https://www.hayadan.org.il/2cometstogether.html
One tail in the morning, a second tail after sunset / a rare event of the passage of two bright comets is expected in the coming days
By Eran Ofek
Photo: Yossi Khouri
Every year several comets pass through the region of the inner solar system, where the Earth is also located, but only once a decade on average can you see a bright comet with the naked eye. The chance of the appearance of two bright comets that can be seen at the same time is even smaller. However, in the coming days, if the predictions come true, it will be possible to witness the rare event - two bright comets will (relatively) approach the Earth and it will be possible to see them without astronomical equipment.
In the past, when astronomical knowledge was extremely limited, comets were considered an ominous sign. Today it is known that comets are lumps of ice, dust and rock that usually orbit the sun in highly elliptical orbits. Most of the time, comets are far from the sun, when they are frozen. When these bodies approach the Sun, to the distance of the Earth from it (about 150 million km), the various ices (for example hydrogen, water and carbon dioxide) turn into gas and create a kind of atmosphere around the comet's core.
Comets are usually very small compared to the planets - their diameter is a few kilometers and their mass is very small. Therefore, the "atmosphere" that is formed is not "attached" to the comet by gravity, and after a relatively short period of time it leaves it. In addition, a stream of particles emitted from the sun at a speed of several hundreds of kilometers per second (a phenomenon known as the "solar wind") pushes the comet's temporary atmosphere in a direction opposite to the sun's direction, thus creating a kind of tail for the comet that accompanies it. The material in the tail is very thin, if it was possible to collect all of it, it would easily fit in the suitcase.
Comets are among the youngest bodies in the solar system, and therefore they can teach us a lot about the process of its formation. In the last 18 years, several spacecraft have passed near comets, photographed them closely and studied their structure, and in the coming years two research spacecraft will collect new data. The American spacecraft Stardust passed near comet Wild-2 in January 2004 and collected samples from its "atmosphere"; The samples will be brought to Earth in January 2006. The European spacecraft Rosetta was launched from Earth in March of this year, will arrive in 2014 at a comet named Churyumov-Garasimenko and will enter orbit around it. It will study the comet thoroughly and will even land a small research probe weighing 100 kg on its surface, which will study its composition and structure, and even photograph its surface.
The comets that will be seen in the coming weeks are called NEAT and LINEAR. They were discovered in 2001 and 2002 while searching for asteroids and comets that could hit the Earth. These surveys also discover many asteroids and comets that do not endanger the Earth, such as NEAT and LINEAR.
NEAT will be seen at its best from Israel starting May 5, when it will be approximately 50 million km from Earth. Between May 5 and 10 it will be possible to see the comet in dark areas outside the city, about 45 minutes after sunset (about 20:30 p.m.), in a southwest-west direction, at a height of about 20 degrees above the horizon. To measure an angle above the horizon, you can take a 30 cm ruler and hold it in a simple, balanced hand forward. When the base of the ruler is visible on the horizon, its upper edge indicates an angular elevation of slightly more than 20 degrees above the horizon.
Comet NEAT will move west and appear higher in the sky each day, until on May 17th it will be seen in the west direction, at a height of about 50 degrees above the horizon (around 20:40). During this period it will probably be possible to notice the comet even in lighted urban areas, but it is recommended to observe both comets outside the city, where the sky is dark.
LINEAR will be a little more difficult to observe, due to its proximity to the Sun. You can see it already these days, only in the early morning hours. The comet will be visible in the eastern direction, about 10 degrees above the horizon, about 45 minutes before sunrise (approximately 05:00). At the end of May, LINEAR will be visible in the evening in the southwest direction, at a height of about 20 degrees above the horizon, at approximately 20:30. But during this period the intensity of his light will be weak and it will be more difficult to notice him. Those interested in seeing it are advised to go outside lighted urban areas.
A rare astronomical event may occur this spring: two comets at the same time
27/2/04
By Avi Blizovsky
A pair of comets that Astronomers have been following for several months may be visible to the naked eye in the spring sky.
Each of them is now visible through the telescope. Scientists can't say exactly what their peak brightness will be, but there is optimism that both may reflect enough light to be seen at about the same time.
For observers in the Northern Hemisphere, chances are that at least one of the comets will provide a spectacular sight. It will take a few more weeks before anything can be said about the chances of the second comet.
"If they are indeed as bright as expected, then both will be visible at the end of April and in part of May," says Dan Green, an astronomer from the Harvard Smithsonian Center for Astrophysics, and director of the Central Astronomical Telegraph Office, which monitors comets, among other things.
"It is rare to see two comets visible in the sky at the same time." According to him, these are objects that were designated C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR). They will probably be called Nit and Linar respectively (Nit and Linar are not comet detectors in the traditional sense, but automatic systems that scan the sky for new comets, and therefore their rate of discovery is greater than any human detector.
Comets are frozen balls of ice and dust that originate in the outer regions of the solar system. They are actually the remains of the creation process - frozen rocks that did not combine to form a planet.
Occasionally gravity pushes them into the inner solar system. When a comet approaches the Sun, solar radiation evaporates material from its surface, and this material surrounds the comet as a halo or head. Sometimes a tail is also formed. The head and tail are actually gas and dust trails visible because they reflect sunlight.
Nite was discovered by the Near Earth Asteroid Tracking (NEAT) program in August 2001. Around that time, its magnitude was 20. On the brightness scale, small numbers (and even negative for some bodies in the Solar System) represent high brightnesses. The faintest object that can be seen when the sky is completely dark is at magnitude 6.5. Nit may reach magnitude 2 or even 1 in late April and remain at this brightness until mid-May. This is according to a notice published by the CFA.
Comet Linar was discovered by the Lincoln Laboratory Near Earth Asteroid Research (LINEAR) project in October 2002. It may be visible to the naked eye as early as mid-March, to experienced observers who will arrive in places where the sky is completely dark.
Uncertainty in forecasts
Astronomers believe that the two comets are now making their way into the inner solar system for the first time, so it is difficult to predict exactly how bright they will reach. "Comets have a lot of unexpected components," says Green.
Some comets disintegrated on the way and thus prevented the chance of reaching high brightness. Others had sudden outbursts that made them much brighter than expected. Others remained unimpressive for as yet unknown reasons.
Comet Nit will first be visible in the Southern Hemisphere sky, while viewers in the Northern Hemisphere will have to wait until the beginning of May. The comet Linar will also be visible in the Southern Hemisphere arrows and depending on its brightness it may be visible a little before sunrise in late April and early May to observers in the Northern Hemisphere.
Astronomer
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