![]() ![]() Since each filter probes distinct altitudes on Neptune, the researchers concluded that the 100 m/s differences they saw must be because the wind speeds change with depth. By observing Neptune in two filters, alternating back-and-forth between the two over a single night, they were able to construct a set of images in both filters that minimized cloud motions between frames in each filter. These wind speed differences may be due to the planet changing over time, or due to observing in different spectral windows.įor the first time, scientists were able to rule out the former explanation. Significant wind speed differences of up to 100 m/s (225 mph) between zonal wind profiles taken in different filters and wavelengths have been observed at Neptune’s equator. Subsequent observations of Neptune with the Keck telescope have provided the latest zonal wind measurements. Voyager 2 took the first measurements of Neptune’s zonal wind profile. This means that the Kp-band can not probe as deep into Neptune’s atmosphere, implying that the ~100 m/s difference in Neptune’s zonal wind profile between filters is due to looking at different altitudes. Credit: Joshua Tollefson More bright features are seen in the H-band than the Kp-band because the Kp-band is more sensitive to methane absorption. Velocities are determined for prominent bright cloud features by tracking their locations frame-by-frame. Each frame is scaled to have the same normalized brightness. A global wind speed profile, called the “zonal wind profile” is formed by combining the velocities of cloud features at different latitudes.įigure 1 – GIFs of Neptune taken in two Keck filters: the H and Kp-bands. Due to Neptune’s fairly quick rotation rate (a day on Neptune is 16 hours), the Coriolis force fixes these features in latitude, similar to how it is difficult to raise or lower your arms if you hold them out while spinning in place very rapidly. This velocity is almost purely in the East-West direction. By tracking the location of each cloud frame-by-frame, a velocity can be determined. Neptune’s wind speeds are derived by tracking bright cloud features as they zip around the planet (Figure 1). In turn, these properties provide clues about the formation history and evolution of Neptune and can help explain how Neptune is powered. The speed and location of these clouds are linked to the atmospheric temperature, composition, and convective motions. In a recent paper, scientists observed bright cloud features on Neptune with the Keck telescope to infer the structure and dynamics of the planet’s upper atmosphere. Voyager 2 found that Neptune emits over twice as much energy as it would receive from solar insolation alone, so some internal force must drive the energetics within Neptune. Thus, it appears that incoming radiation alone can not power the extreme winds on Neptune. ![]() How these blustering winds are sustained is a mystery to planetary scientists – Neptune is 30 times farther away from the Sun than Earth is, meaning the planet receives 900 times less flux than the Earth. Neptune’s upper atmosphere contains some of the fastest winds in the solar system, reaching speeds upwards of 400 m/s (900 mph). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |