The Venus transit of 2012 allowed us to measure the solar radius around 6173Å with HMI: we obtained a value of 959.58″ at 1 AU, with a systematic uncertainty larger than 0.27″.
We present observations from SDO/HMI of a magnetic transient observed in NOAA 11429 during the M7.9 flare on 13 March 2012. The observed transient showed an impulsive rotation of the field vector in response to the white-light flare.
We analyze umbral area, magnetic field, and umbral intensity of the sunspots during the rising phase of cycle 24. We do not find a significant variation in either sunspot physical properties or distribution of sunspot umbral area from previous cycles.
Solar meridional circulation, if mechanically driven and thermally
braked, contains two cells in latitude; generating two cells in depth,
recently observed by SDO/HMI, is a new challenge to theory.