![]() ![]() You are also told that in the coming week, all 7 are destined to join the solar wind, one day apart. You are told that 7 ions are located at that point, close to each other and on the same magnetic field line. Mark with the number 1 the point where the line furthest to your right emerges from the Sun.or counterclockwise?ĭecide for yourself and write it down-no peeking! Since the Sun is viewed here from north, and it rotates in the same sense as the Earth, on this scale drawing, does it rotate clockwise.A version with higher resolution is linked here you will not see any difference on your screen, whose resolution is limited to 72 dpi, but you can copy the file and use it with some graphic program that has higher resolution.) (As a shortcut, you can download the drawing here. We will now derive the shape of those lines. The magnetic field at all these points is already so weak that the solar wind overpowers it and shifts its field lines, while its own motion-radially outward-remains unchanged. Besides, the solar wind does not start moving from the Sun's surface, but from some greater distance.) ( Yes, the Sun is drawn much too big on this scale, but we will ignore the difference this makes. Each interval marks the distance the solar wind covers in one day. On each of the spokes, mark the point where it emerges from the Sun, and mark from there, along each spoke, additional points at intervals of 1.5 inches.Extend the lines until they reach within 1 cm of the sides or 3 cm of the top.) On that line mark points at distances 15/16", 2" and 3 3/8" on both sides of the y-axis, then draw radial lines from the center of the Sun through those points, extending them until they are 1/2" from the sides of the sheet or 1" from the top.įor those used to metric units, let the radius of the Sun be 1 cm (diameter=2cm), the pencil line follows y=10 cm and the marks on it are at distances of approximately 23.7, 50.2 and 83.9 millimeters from the y-axis. With a pencil, draw faintly the line y=4, parallel to the x axis but 4" (4 inches) above it. Draw the two axes, with the y-axis extending to near the top of the page. ( Alternative method: Let center of the Sun be the origin of a system of cartesian coordinates, with the x-axis parallel to the bottom of the page. Using a protractor and a ruler, draw on each side of that line 3 additional radial "spokes" from the center of the Sun, each making angles of 13.3° with its neighbors. If the Sun rotates once in 27 days, then each day it rotates byĭraw from the center of the Sun a line perpendicular to the bottom of the page, extending most of the way to the top. In the middle of the bottom (short side) of a sheet of paper, draw a small circle, about one inch across: that will represent the Sun, viewed from far above its north pole.Using this "law of field line preservation", we will now derive the shape of interplanetary magnetic field lines. ![]() (For any space physicist reading this: the deformation process also involves electric fields.) If they then manage to move, the field line gets deformed: it is as if the magnetic field is "frozen" into the plasma. If two or more ions start out located on the same field line, they will always share the same field line. A rule which is fairly well obeyed states then that: That is why magnetic field-line loops tend to keep back the solar wind, unlike the outward-bound lines in the "coronal holes" between them.īut if the field is weak, then the plasma rules and pushes the field lines around. If the magnetic field is strong-as happens in the corona, close to the Sun-then it dominates, and determines where the plasma can or cannot go. When some process moves plasma inside a magnetic field, what happens depends of the relative strength of the two. Here this "dragging" process will be explained, and it will be used to obtain the expected shape of those field lines. From the observed direction of interplanetary magnetic field lines (or "interplanetary lines of force"), we believe this field comes from the Sun, carried by magnetic field lines dragged out by the solar wind. The field may be weak, but it extends over huge distances, and can have important effects. When a spacecraft breaks away from the influence of the Earth's magnetic field into interplanetary space, it finds there a weak magnetic field. ![]() #18-A Interplanetary Magnetic Field Lines An optional activity, to draw the expected shapes ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |