天文单位（Astronomical Unit，简称AU）是衡量天体之间距离的一种单位，它约等于地球与太阳之间的平均距离。最初，天文单位是基于地球绕太阳运行轨道的椭圆形状，定义为椭圆轨道的半长轴长度。In 1976, the International Astronomical Union (IAU) redefined the astronomical unit to be the distance at whi...
Play with our timeline to see the swings in the planets’ distances from Earth. Moon Phase and Position Find the Moon’s illumination, distance, and latitude for any time on any date. Meteor Showers Check the best dates and timings to see shooting stars from your location. What Is a Conju...
Play with our timeline to see the swings in the planets’ distances from Earth. Moon Phase and Position Find the Moon’s illumination, distance, and latitude for any time on any date. Meteor Showers Check the best dates and timings to see shooting stars from your location. What Is a Conju...
Red Sun Systems - T'au probes have marked the dense cluster of planets around a string of six distinct red suns; however, the massive Ork population has deterred any further T'au colonisation of the region. The star systems are ringed with T'au sensor buoys, in hopes of offering early ...
There is an overall agreement between the model results and solar wind observations at different latitudes and heliocentric distances. Statistical analysis for Year 2007 reveals that our model can predict most of the corotation interaction regions, high﹕peed streams, and magnetic sector boundaries at ...
(60558) 174P/Echeclus is an unusual object that belongs to a class of minor planets called Centaurs, which may be intermediate between Kuiper Belt Objects and Jupiter Family comets. It is sporadically active throughout its orbit at distances too far for water ice to sublimate, the source of...
and there will come a point where there will be no more heat, no more light, just inert matter scattered over incalculable distances. To make all the essential concepts clear, we reworked the village almost a dozen times. For seven years, we were discovering new problems of the same kind....
et al. Mapping distances across the Perseus molecular cloud using CO observations, stellar photometry, and Gaia DR2 parallax measurements. Astrophys. J. 869, 83 (2018). ADS Google Scholar Stephens, I. W. et al. Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES)—...
diameter—of Earth’sellipticalorbitaround the Sun. The astronomical unit provides a convenient way to express and relate distances of objects in the solar system and to carry out various astronomical calculations. For example, stating that theplanetJupiteris 5.2 AU (5.2 Earth distances) from the ...
On the formation of our solar system and many other protoplanetary systems observed by ALMA and SPHERE In view of the many recent observations conducted by ALMA and SPHERE, it is becoming clear that protoplanetary disks form planets in narrow annular gaps at various distances from the central prot...