![]() If you double your mass, gravity pulls on you twice as hard. First, it depends on your mass and the mass of the planet you are standing on. This force of gravity depends on a few things. The Relationship Between Gravity and Mass and DistanceĪs stated above, your weight is a measure of the pull of gravity between you and the body you are standing on. It still has inertia, and hence mass, yet it has no weight. If you grabbed the anvil and tried to shake it, you would have to push it to get it going and pull it to get it to stop. Are you or the anvil mass-less? Absolutely not. If you are in a spaceship far between the stars and you put a scale underneath you, the scale would read zero. This force of attraction between you and the Earth (or any other planet) is called your weight. How? All you have to do is stand on a scale! Scales measure the force of attraction between you and the Earth. For everyday-sized objects, this gravitational pull is vanishingly small, but the pull between a very large object, like the Earth, and another object, like you, can be easily measured. The amount of attraction depends on the size of the masses and how far apart they are. Every object in the universe with mass attracts every other object with mass. Mass is a measure of how much inertia an object displays. This quality or "sluggishness" of matter is its inertia. Once you've got it moving, it wants to stay moving. If the stone is at rest, it wants to remain at rest. If you shake an object like a stone in your hand, you would notice that it takes a push to get it moving, and another push to stop it again. An object with mass has a quality called inertia. The mass of a body is a measure of how much matter it contains. We often use the terms "mass" and "weight" interchangeably in our daily speech, but to an astronomer or a physicist they are completely different things. The trail fitting algorithm can be implemented at the source detection level for all detections to provide trail length and position angle that can be used to reduce the false tracklet rate.Before we get into the subject of gravity and how it acts, it's important to understand the difference between weight and mass. For trails longer than about 10 pixels (∼3× PSF) our trail fitting provides ∼3× better astrometric accuracy and up to two magnitudes improvement in the photometry. For short trails our trailing function yields the same astrometric and photometry accuracy as a functionally simpler two-dimensional Gaussian but the latter underestimates the length of the trail-a parameter that can be important for measuring the object’s rate of motion and assessing its cometary activity. We have fit the function to both synthetic and real trailed asteroid detections from the Pan-STARRS1 survey telescope to obtain accurate astrometry and photometry. ![]() We present an analytic function describing a trailed detection under the assumption of a Gaussian point spread function (PSF) and constant rate of motion. Their recovery, especially on their discovery apparition, depends upon obtaining good astrometry from the trailed detections. Nearby asteroids in particular typically have high apparent rates of motion and acceleration. Asteroid detections in astronomical images may appear as trails due to a combination of their apparent rate of motion and exposure duration. ![]()
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