Event Date: September 3rd
Time: 4:17 AM
Time: 4:17 AM
Brief
We are 5 mornings away from a very fine sight. That is, for most of August, I have talked about the "2nd/other triangle" in the east, while our main Summer Triangle of (V)ega/(D)eneb/(A)ltair. sets earlier each morning in the northwest. (V)enus/(J)upiter/(S)irius have been changing triangular configuration daily as Venus has separated from Jupiter. Although Jupiter has changed separation from Sirius, it has been much slower than Venus, which moves much faster than prograde than Jupiter. Getting back to the aforementioned 5-morning forecast, this V/J/S triangle will look more and more isosceles. It is larger than the size as V/D/A, with current separations of 39º, 42º, 47º (V/S, V/J, J/S respectively).
Below is a 180º full-zoomout of the sky, to display both triangles. This interesting feature of the software lets us see the triangles at the same time; our normal vision of 100º doesn't let us do this normally.
We are 5 mornings away from a very fine sight. That is, for most of August, I have talked about the "2nd/other triangle" in the east, while our main Summer Triangle of (V)ega/(D)eneb/(A)ltair. sets earlier each morning in the northwest. (V)enus/(J)upiter/(S)irius have been changing triangular configuration daily as Venus has separated from Jupiter. Although Jupiter has changed separation from Sirius, it has been much slower than Venus, which moves much faster than prograde than Jupiter. Getting back to the aforementioned 5-morning forecast, this V/J/S triangle will look more and more isosceles. It is larger than the size as V/D/A, with current separations of 39º, 42º, 47º (V/S, V/J, J/S respectively).
Below is a 180º full-zoomout of the sky, to display both triangles. This interesting feature of the software lets us see the triangles at the same time; our normal vision of 100º doesn't let us do this normally.
 | |
|
Detailed
The V/D/A stars have separations only as large as 38º (V/A). If you have looked in the sky at V/D/A and imagine it about 25% larger, that is about the size of V/J/S. Also, since Altair now is low in atmospheric pollution as early as 4 AM, Sirius is just starting to rise at this time. For how many minutes can you see all 6 stars while Sirius and Altair are low? Vega is about as low as Altair, yet sets a little later being further north. At the time above, Altair and Sirius are about the same altitude. Now that they are rising before twilight, both may be easy enough to see with binoculars, even with heavy atmospheric pollution.
Keep watching V/J/S, as Venus continues to pull away from both slightly. Can you see how two "sides" are starting to look the same "length" as a result of the separations? Look closely, and use your fist stretched out at arm's length if that helps measure them. Remember that a fist is about 10º held out this way, with each knuckle about 2º.
No comments:
Post a Comment