# Near-Real-Time Global Thermospheric Density Variations Unveiled by Starlink Ephemeris
## 3 Results
Specifically, the LT of STARLINK-44934's ascending node at the equator shifted from \(\sim\)09:40 on 2 October to \(\sim\)23:55 on 29 October, while STARLINK-46047's LT transitioned from \(\sim\)19:40 on 2 October to \(\sim\)09:40 on 29 October. Clearly, both Figure 5c,d exhibit a trend of high-value regions shifting from the Southern Hemisphere to the Northern Hemisphere over this month. This phenomenon arises because the region of maximum density along an orbit corresponds to the LT of noon, and as UT progresses, the geographic location associated with a specific LT gradually migrates from the Southern to the Northern Hemisphere. Consequently, when STARLINK-46047 crosses the equator at 12:00 LT, its high-value regions are nearly symmetrically distributed between the two hemispheres, as the results showed on nearly 23 October. As previously noted, STARLINK-44934 operates primarily at the dawn and nightside (ascending nodes), while STARLINK-46047 is active at the dusk and dayside (ascending nodes). Figure 5c,d reveal that the mechanical energy loss of the former is consistently lower than that of the latter, which aligns with the expected lower thermospheric density at the nightside due to the absence of solar radiation. Both results of the dayside and nightside indicate responses to the 11 October geomagnetic disturbance, though the dayside manifests a more pronounced reaction (characterized by significant enhancements in mechanical energy loss) compared to the nightside. This day-night asymmetry in thermospheric density enhancement aligns well with the findings of [PERSON] et al. [47]. However, unlike Swarm-B, STARLINK-46047's response to storms lags by a few hours. This delay stems from the Starlink ephemerides update cycle, which occurs every \(\sim\)8 h. During each update, the latest space environment conditions are incorporated for orbit extrapolation. Consequently, if a space weather event occurs between two consecutive batches, the resulting data discontinuity manifests as sharp boundaries in the STARLINK-46047 data on 8 October and 11 October, coinciding with the two geomagnetic storms. These results also indicate that, during rapidly evolving storms, discrepancies may emerge between the predicted and actual atmospheric density variations until the next scheduled update. The post-storm overcooling phenomenon is also evident in the STARLINK-46047 data following the 11 October storm. However, unlike Swarm-B, the thermosphere density reflected in STARLINK-46047 recovered earlier. This difference is attributed to STARLINK-46047's LT gradually shifting toward noon, resulting in greater solar radiation exposure compared to Swarm-B, which maintained a relatively constant LT of \(\sim\)09:40. To further validate the Starlink satellite results, we aligned the LTs with Swarm-B by selecting data from 10 Starlink satellites whose equator-crossing LTs of ascending nodes were approximately 09:40 at different periods. These data were combined to create a continuous dataset, as shown in Figure 5e, where results from individual Starlink satellites are demarcated by red dashed vertical lines. In Figure 5e, after accounting for LT variations, the mechanical energy loss exhibits patterns remarkably similar to those of Swarm-B in Figure 5b, including comparable responses to geomagnetic storms, recovery rates, and the duration and intensity of the post-storm overcooling phenomenon. This compelling agreement strongly validates the utility of Starlink ephemeris data for thermospheric and space weather monitoring.