CATCH A STAR

Object - EUROPA

This work was made by

ALEXANDRA SOFIA SILVA (Student) - alexandrasofia2@portugalmail.pt

BEATRIZ CACHIM (Teacher) - bcachim@netvisao.pt

School :

Escola Secundária c/ 3CEB Afonso de Albuquerque

School Adress :

Rua Comandante Salvador do Nascimento

6300-705 Guarda

PORTUGAL


SUMMARY

   

1

Introduction

2

Jupiter – The main Planet

3

Historical aspects

4

Europa Main Characteristics (the biography of a moon)

5

 Images    

6

 The terrestrial moon and europa  

7

 A litle test about Europa  

8

Bibliography

9

Identification

1. INTRODUCTION

Fig. 1 - This it is one of the highest resolution images of Europe obtained by Voyager 2.

Europa is, perhaps, the most interesting of the Jupiter satellites.

It has an amazing web of straight and curve intersecting lines, that, sometimes, remind a billiard ball. But that’s not all. It, seems that Europa has a salted ocean under the surface, and, employing the Hubble Space Telescope from NASA, astronomers have identified the presence of an extremely thin atmosphere of molecular oxygen around it.

Scientists predicted the presence of water in Europa, but they could not verify that until now. The presence of oxygen is not a sign of life existence there. Europa is 780 millions km away from the Sun and have a very cold surface, about –145ºC. so it’s not possible to find life there in the way we know it on Earth. Europa oxygen is generated in non biological methods.

Although it has a few impact craters, the surface seems young and has tectonic movements. The surface is, in fact, covered with a thick layer of ice

There are some dark spots, no more than 10km longer, and speculations about the dark lines seen at the surface being the result of tectonic movements, leading to fissures in the crust, filled with material from the inner side, probably salt water, have been made.

Europa is very different from the other three galilean satellites and its surfaces is very regular, in opposition to the other objects of the solar system. Its shiny surface, has few craters with more than 50 km of diameter, which suggests that it is relatively young. The fissures indicate an expansion of the crust of ice that covers it, under which it’s suspected the existence of a silicate blanket or of a great water ocean.

2 - JUPITER – THE MAIN PLANET

Statistical data about Jupiter

Equatorial diameter

142 800 Km

Inclination

3,12º

Eccentricity

0,048

Mass

1,9x10 27 kg, that is, 317,8 the Earth mass

Average density

1,34g/cm 3

Surface gravity

2,4 the Earth gravity

Escape velocity

60 Km/s

Average distance to the Sun

780 000 000 Km

Orbital Period

11,86 years

Orbit Speed

13,1 km/s

Rotation Period

9,84 hours

Period

398,88 Earth days

Visual Albedo

0,51

3 - HISTORICAL ASPECTS

Europa was discovered by Galileo Galilei. Visiting Venice, in 1609, Galileo was told that dutch optical lenses manufacturers made tubes with lenses inside. This optical evolution interested Galileo and he began to make his own instruments.

He saw Europa, for first time, in the 7th January 1610; by that time Galileo saw four little light dots, near Jupiter, that were changing places in few hours.

In the beginning he thought there were three stars near Jupiter, but next day at night the “stars were there but in different positions and it seemed they moved the wrong way. The next week Galileo observed those “stars” again. He realised that the stars were always in Jupiter vicinity moving with it, and changed positions relative to each other and Jupiter too. Finally Galileo was led to the conclusion that the “stars” were not “real stars” but planetary bodies in orbit around Jupiter. This was very important to support the Copernican theory, because it proved that there were things in Universe that did not revolve around the Earth.

      

Fig. 2 - Galileo manuscript

In March 1610 Galileo published his observations in Siderius Nuncius like this: “ I should disclose and publish to the world the occasion of discovering and observing four Planets, never seen from the beginning of the world up to our own times, their positions, and the observations made during the last two months about their movements and their changes of magnitude; and I summon all astronomers to apply themselves to examine and determine their periodic times, which it has not been permitted me to achieve up to this day... On the 7th day of January in the present year, 1610, in the first hour of the following night, when I was viewing the constellations of the heavens through a telescope, the planet Jupiter presented itself to my view, and as I had prepared for myself a very excellent instrument, I noticed a circumstance which I had never been able to notice before, namely that three little stars, small but very bright, were near the planet; and although I believed them to belong to a number of the fixed stars, yet they made me somewhat wonder, because they seemed to be arranged exactly in a straight line, parallel to the ecliptic, and to be brighter than the rest of the stars, equal to them in magnitude...When on January 8th, led by some fatality, I turned again to look at the same part of the heavens, I found a very different state of things, for there were three little stars all west of Jupiter, and nearer together than on the previous night

By the same time, the german astronomer Simon Marius, claimed to have seen the Jupiter moons in November 1609, but he did not publish his observations, so it was not possible to verify. But the names given to the galilean satellites were the Marius names, based on a Kepler’s suggestion, that he explains this way: ” Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River, Inachus, Callisto of Lycaon, Europa of Agenor. Then there was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell.... I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto...

4 - EUROPA MAIN CHARACTERISTICS (the biography of a moon)

One of the 4 bigger, among the 39 satellites around Jupiter, Europa is easily seen. It is enough to use binoculars.

  Fig. 3     -  Jupiter family    

Europa is 670 900 Km apart from Jupiter and its mass is about 0,67 the earth Moon’s mass, that is 4,80x10 22 kg.

Fig. 4 - Internal structure of Europe

This sight in cut shows what scientist think is the internal structure of Europe.

It was created from images obtained in 1979 by the spacecraft Voyager from NASA. The interior characteristics are deduced by the measures of the gravitational and magnetic fields obtained by the Galileo. Europa’s ray measures 1565 km

Europa, one of the four bigger Jupiter satellites, is probably composed of layers. It has a metallic core where iron and nickel can be found (grey in the image), surrounded by rock shells (drawn in brown). This rock shell is surrounded by liquid or icy water, (can be seen in blue and white). The outer layer is represented in white to show that it is different from the others; it could suggest an ice layer overlying a liquid water ocean. Galileo images of Europa suggest that the hypothetical liquid water ocean might now underlie a surface ice layer several to 10 kilometres thick; however, this evidence is also consistent with the existence of a liquid water ocean in the past. It is not certain if there is a liquid water ocean on Europa at present

Similar, in size, to the terrestrial moon, Europa has an icy surface that is very cracked.

Scientists believe Europa has 2,90 x 10 9 Km 3 of water and its diameter is 3,130 Km.

Its rotational period is 3,55 terrestrial days; The density is 2,99 g/cm 3 and, concerning to gravity acceleration, Europa has the lowest if compared to Earth and terrestrial moon. The highest peak is 900 meters.

  Fig. 5     -  Broken ice in Europa    

This image covers part from the equatorial zone of Europe and was covers a distance of 156,000 kilometres

It seems that Europa may have an ocean below its surface. Scientists say that curved cracks on the frozen surface of Europa may be evidence that a deep ocean of liquid water covers the globe below its icy crust. The surface markings, are very different of all the solar system. They have been mystery to scientists since they were first saw.

Some of the cracks are more than 100 kilometres long and are linked in chains that span hundreds of kilometres. Perhaps the cracks were caused by Jupiter's strong gravitational pull. When Europa is closer to Jupiter, the tides of the ocean rise as high as 30 meters, causing the ice on the surface to crack. As Europa rotates, the cracks become curved. The curving continues until the pull of gravity from Jupiter weakens as Europa moves away from the planet. When Europa's orbit brings it closer to Jupiter again, a new arc forms and the process starts again.

Scientists also say that if a liquid ocean exists on Europa, it is possible that it may provide a hospitable environment for life forms to exist. To find out, NASA is planning to launch a new spacecraft to orbit Europa in 2003. It will carry ice-penetrating radar to probe deeper below Europa's surface.

5 - IMAGES

  Fig.    6        -    Jupiter and moons  

Fig. 7 - Jupiter and moons

    

  Fig.    8   - Jupiter moons    

Fig. 9 - Jupiter and Europa

    

  Fig. 10    -   Europa surface    

Fig. 11 - Europa close up

    

  Fig. 12    - Cratera Pwyll in Europa    

Fig. 13 - Cratera Tyre in Europa

    

  Fig. 14    - Europa    

Fig. 15 - Europa

        

  Fig.    16   - Europa full face    

Fig. 17 - Europa; obtained by Voyager 2

    

  Fig.    18   - Imaginative painting about Europa    

Fig. 19 - The Cracked Ice Plains of Europa

    

  Fig.    20    -   Thera and Thrace Macula on Europa    

Fig. 21 - two global views from Galileo

6 - THE TERRESTRIAL MOON AND EUROPA

 

EUROPA

MOON

Image

Fig. 22 - Europa

Fig. 23 - Moon

Discovery

 7 January 1610 by Galileo Galilei in Padua, Italy and Simon Marius in Germany by the same time.  
 Has been known since prehistoric times    

Name origin

Europa was a Phoenician princess
 It was called Luna by the romans and Selene or Artemis by the greek.  

Surface composition

Mainly water and ice

Rocks

Surface

Shiny and very few craters

Many impact craters

Visual Albedo

0,64

0,12

Highest peack

900m

100 to 200 m

Average diameter

3130km

3474 km

Average distance to main planet

670 900 km

384 000 km

Average distance to Sun

5,203 A.U.

1 A.U.

Period

3,55 Earth days

27,3 days

Eccentricity

0,009

0,055

Orbit inclination

0,470 degrees

5,145 degrees

Orbit velocity

13,74 km/s

1 kms -1

Mass

4,80x10 22 kg

7,35 x 10 22 kg

Gravity (Earth=1)

1,3 ms -2

1,62 ms -2

Density

2,99 gcm -3

3,35 gcm -3

Escape velocity

2,02 km/s

2,38 km/s

Orbital period

3,55 Earth days

27,3 days

Rotacional period

3,55 Earth days

27,3 days

Average surface temperature

-145 ºC

Day time: 107 ºC

Night time: -153 ºC

  
  7 - A LITLE TEST ABOUT EUROPA   
  
  1.    Europa is:  
  a)    a continent.  
  b)    a rock.  
  c)    a natural satellite.  
  c)    an artificial satellite.  
    
  2.    Historically Europa was discovered by:  
  a)    Isaac Newton.  
  b)    prehistoric men.  
  c)    Albert Einstein.  
  c)    G  alileo   Galilei.  
    
  3.    The name Europa was proposed by Simon Marius under suggestion of:  
  a)    the european citizens.  
  b)    Johannes Kepler.  
  c)    Aristotle.  
  c)    Galileo Galilei.  
    
  4.    The Europa surface has lines. Maybe it is due mainly to:  
  a)    the existence of ice.  
  b)    shiny rocks.  
  c)    UFO landing.  
  c)    impact craters.  
    
  5.    Europa is a satellite of:  
  a)    Earth.  
  b)    Mars.  
  c)    Jupiter.  
  c)    Saturn.  
    
  6.    Scientist think that under the surface Europa has:  
  a)    a lake.  
  b)    gas.  
  c)    a salt water ocean.  
  c)    rocks.  
    

8-BIBLIOGRAPHY

·          Forey, P, et al, “Estrelas e Planetas”, Plátano, Edições Técnicas, Barcelona, 1990

·        Ferreira, M, et al, “Introdução à Astronomia e às Observações Astronómicas”, Plátano, Edições Técnicas, Lisboa, 1995

·        Burnham, R, et al, “Astronomía”, Blume, Barcelona, 2002

·        Bon, P, et al, “O Universo”, Ed. Fleurus Livros e Livros, Lisboa 2000

·        http://www.phschool.com/science/planetdiary/archive/astr1092599.html

·        http://solarsystem.nasa.gov/features/planets/jupiter/jupiter.html

·        http://nautilus.fis.uc.pt/astro/mirror/np/np-p/europa.html

·        http://www.iis.com.br/~lgabriel/spanish.htm

·        http://www.starstuff.org/default.asp?cover=/articles/881.asp

·        http://wwwalu.por.ulusiada.pt/21562197/alua.htm

IDENTIFICATION

Made by:

Alexandra Silva –Student- alexandrasofia2@portugalmail.pt

  Beatriz Cachim    –Teacher- bcachim@netvisao.pt  

School: Escola Secundária c/ 3CEB Afonso de Albuquerque

School Address: Rua Comandante Salvador do Nascimento, 6300-705 Guarda – Portugal